diff --git a/CHANGES.rst b/CHANGES.rst
index 61488c7b..de149cf4 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -3,6 +3,8 @@ pywb 0.7.2 changelist
 
 * Experiment with disabling DASH for YT
 
+* New ``req_cookie_rewrite`` rewrite directive to rewrite outgoing ``Cookie`` header, can be used to fix a certain cookie for a url prefix.
+
 
 pywb 0.7.1 changelist
 ~~~~~~~~~~~~~~~~~~~~~
@@ -25,7 +27,7 @@ pywb 0.7.1 changelist
   - setAttribute override
   - Date override sets date to replay timestamp
   - Image() object override
-  - ability to disable dynamic attribute rewriting by setting `_no_rewrite` on an element.
+  - ability to disable dynamic attribute rewriting by setting ``_no_rewrite`` on an element.
 
 * Type detection: resolve conflict between text/html that is served under js_ mod, resolve if html or js.
 
diff --git a/pywb/rewrite/rewrite_live.py b/pywb/rewrite/rewrite_live.py
index 1b20e120..3ebbe68d 100644
--- a/pywb/rewrite/rewrite_live.py
+++ b/pywb/rewrite/rewrite_live.py
@@ -50,10 +50,11 @@ class LiveRewriter(object):
 
         return (status_headers, stream)
 
-    def translate_headers(self, url, env):
+    def translate_headers(self, url, urlkey, env):
         headers = {}
 
         splits = urlsplit(url)
+        has_cookies = False
 
         for name, value in env.iteritems():
             if name == 'HTTP_HOST':
@@ -73,6 +74,11 @@ class LiveRewriter(object):
             elif name == 'HTTP_REFERER':
                 continue
 
+            elif name == 'HTTP_COOKIE':
+                name = 'Cookie'
+                value = self._req_cookie_rewrite(urlkey, value)
+                has_cookies = True
+
             elif name.startswith('HTTP_'):
                 name = name[5:].title().replace('_', '-')
 
@@ -87,9 +93,28 @@ class LiveRewriter(object):
             if value:
                 headers[name] = value
 
+        if not has_cookies:
+            value = self._req_cookie_rewrite(urlkey, '')
+            if value:
+                headers['Cookie'] = value
+
         return headers
 
+    def _req_cookie_rewrite(self, urlkey, value):
+        rule = self.rewriter.ruleset.get_first_match(urlkey)
+        if not rule or not rule.req_cookie_rewrite:
+            return value
+
+        for cr in rule.req_cookie_rewrite:
+            try:
+                value = cr['rx'].sub(cr['replace'], value)
+            except KeyError:
+                pass
+
+        return value
+
     def fetch_http(self, url,
+                   urlkey=None,
                    env=None,
                    req_headers=None,
                    follow_redirects=False,
@@ -109,7 +134,7 @@ class LiveRewriter(object):
             method = env['REQUEST_METHOD'].upper()
             input_ = env['wsgi.input']
 
-            req_headers.update(self.translate_headers(url, env))
+            req_headers.update(self.translate_headers(url, urlkey, env))
 
             if method in ('POST', 'PUT'):
                 len_ = env.get('CONTENT_LENGTH')
@@ -155,17 +180,18 @@ class LiveRewriter(object):
         if url.startswith('//'):
             url = 'http:' + url
 
+        # explicit urlkey may be passed in (say for testing)
+        if not urlkey:
+            urlkey = canonicalize(url)
+
         if is_http(url):
-            (status_headers, stream) = self.fetch_http(url, env, req_headers,
+            (status_headers, stream) = self.fetch_http(url, urlkey, env,
+                                                       req_headers,
                                                        follow_redirects,
                                                        ignore_proxies)
         else:
             (status_headers, stream) = self.fetch_local_file(url)
 
-        # explicit urlkey may be passed in (say for testing)
-        if not urlkey:
-            urlkey = canonicalize(url)
-
         if timestamp is None:
             timestamp = datetime_to_timestamp(datetime.datetime.utcnow())
 
diff --git a/pywb/rewrite/rewriterules.py b/pywb/rewrite/rewriterules.py
index 514fb55e..95e2225a 100644
--- a/pywb/rewrite/rewriterules.py
+++ b/pywb/rewrite/rewriterules.py
@@ -8,6 +8,7 @@ from header_rewriter import HeaderRewriter
 from html_rewriter import HTMLRewriter
 
 import itertools
+import re
 
 
 #=================================================================
@@ -47,6 +48,12 @@ class RewriteRules(BaseRule):
         # cookie rewrite scope
         self.cookie_scope = config.get('cookie_scope', 'default')
 
+        req_cookie_rewrite = config.get('req_cookie_rewrite', [])
+        for rc in req_cookie_rewrite:
+            rc['rx'] = re.compile(rc.get('match', ''))
+
+        self.req_cookie_rewrite = req_cookie_rewrite
+
     def _add_custom_regexs(self, field, config):
         regexs = config.get(field + '_regexs')
         if not regexs:
diff --git a/pywb/rewrite/test/test_rewrite_live.py b/pywb/rewrite/test/test_rewrite_live.py
index fdea7557..99fb6074 100644
--- a/pywb/rewrite/test/test_rewrite_live.py
+++ b/pywb/rewrite/test/test_rewrite_live.py
@@ -22,10 +22,43 @@ def test_csrf_token_headers():
     rewriter = LiveRewriter()
     env = {'HTTP_X_CSRFTOKEN': 'wrong', 'HTTP_COOKIE': 'csrftoken=foobar'}
 
-    req_headers = rewriter.translate_headers('http://example.com/', env)
+    req_headers = rewriter.translate_headers('http://example.com/', 'com,example)/', env)
 
     assert req_headers == {'X-CSRFToken': 'foobar', 'Cookie': 'csrftoken=foobar'}
 
+def test_req_cookie_rewrite_1():
+    rewriter = LiveRewriter()
+    env = {'HTTP_COOKIE': 'A=B'}
+
+    urlkey = 'example,example,test)/'
+    url = 'test.example.example/'
+
+    req_headers = rewriter.translate_headers(url, urlkey, env)
+
+    assert req_headers == {'Cookie': 'A=B; FOO=&bar=1'}
+
+def test_req_cookie_rewrite_2():
+    rewriter = LiveRewriter()
+    env = {'HTTP_COOKIE': 'FOO=goo'}
+
+    urlkey = 'example,example,test)/'
+    url = 'test.example.example/'
+
+    req_headers = rewriter.translate_headers(url, urlkey, env)
+
+    assert req_headers == {'Cookie': 'FOO=&bar=1'}
+
+def test_req_cookie_rewrite_3():
+    rewriter = LiveRewriter()
+    env = {}
+
+    urlkey = 'example,example,test)/'
+    url = 'test.example.example/'
+
+    req_headers = rewriter.translate_headers(url, urlkey, env)
+
+    assert req_headers == {'Cookie': '; FOO=&bar=1'}
+
 def test_local_1():
     status_headers, buff = get_rewritten(get_test_dir() + 'text_content/sample.html',
                                          urlrewriter,
diff --git a/pywb/rules.yaml b/pywb/rules.yaml
index da47efad..cb87a843 100644
--- a/pywb/rules.yaml
+++ b/pywb/rules.yaml
@@ -162,7 +162,7 @@ rules:
             args:
                 - id
                 - itag
-                - mime
+                  #- mime
 
           filter:
               - '~urlkey:{0}'
@@ -187,15 +187,24 @@ rules:
           js_rewrite_location: location
 
 
-    # watch config changes
-    - url_prefix: 'com,youtube)/watch'
+    # watch and embed config changes
+    - url_prefix: 'com,youtube)/'
 
       rewrite:
-
         js_regexs:
             - match: 'ytplayer.load\(\);'
               replace: 'ytplayer.config.args.dash = "0"; ytplayer.config.args.dashmpd = ""; {0}'
 
+            - match: 'yt\.setConfig.*PLAYER_CONFIG.*args": {'
+              replace: '{0} "dash": "0", dashmpd: "", '
+
+        req_cookie_rewrite:
+            - match: '^(((?!PREF).)*)$'
+              replace: '\1; PREF=f2=40000000'
+
+            - match: '(.*PREF=)([^ ;]*)(.*)'
+              replace: '\1&f2=40000000\3'
+
     # testing rules -- not for valid domain
     #=================================================================
     # this rule block is a non-existent prefix merely for testing
@@ -217,6 +226,15 @@ rules:
       rewrite:
         js_rewrite_location: urls
 
+        req_cookie_rewrite:
+            - match: '^(((?!FOO).)*)$'
+              replace: '\1; FOO=bar=1'
+
+            - match: '(.*FOO=)([^ ;]*)(.*)'
+              replace: '\1&bar=1\3'
+
+            - match: ''
+              invalid_: ''
 
       # all domain rules -- fallback to this dataset
     #=================================================================