''locking this thread as duplicate, please continue at [https://support.mozilla.org/en-US/questions/1054701 /questions/1054701]'' From last week embedded videos have stopped playing. I tried it on different and fresh Firefox profiles but it wont work. For example it doesn't work on this page http://www.fastcompany.com/3044043/most-creative-people/stanfords-most-popular-class-isnt-computer-science-its-something-much-m But If got to youtube.com the videos play just fine. I cleared cookies after reading some similar issue on support forum of Firefox but it didn't work. Please help.