Firefox has this : *https://www.bleepingcomputer.com/news/software/firefox-will-now-delay-the-loading-of-tracking-scripts/ As says can sometimes break a page. Update Video Card Drivers. Please Refresh but do this 1st: *https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer *https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles then *https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings TEST....... If no issues then Extensions which need to be added back in 1 at a time and tested ..... Or it is your Profile : Make a new one and test ...: *https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles If is your Profile : *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile *http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox Note: Any customization will revert back to default, you will also need to reinstall Extensions. Please let us know if this solved your issue or if need further assistance.

''EmbraceTheBald [[#question-1196173|said]]'' <blockquote> Video on twitter(and Embedded twitter vids on outside sites) get "The Media Could not be played" error msg. I went here and all check marks are blue, yet videos still do not work. https://www.youtube.com/html5/ They work on Chrome & Safari, and I did not start seeing this problem until upgrade to FF Quantum </blockquote> Not necessary a bug in Firefox. https://support.mozilla.org/en-US/questions/1195465#answer-1051992

^: You can check the Web Console for error messages to see if this is the same CSP issue. *"3-bar" menu button or Tools -> Web Developer