http://www.ghacks.net/2014/06/13/fix-error-occurred-please-try-later-youtube-error/ https://www.reddit.com/r/firefox/comments/hn6lvd/youtube_videos_not_playing_in_firefox_only/

Try to set the Shockwave Flash plugin to "Never Activate". Do you use a bookmark or are you starting with the main (home) page of this website? If you use a bookmark to access a specific page then instead navigate to this page starting with the main page or with the sign in page in case there is a problem with this bookmark. ----- You can try these steps in case of issues with web pages: You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files. *hold down the Shift key and left-click the Reload button *press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux) *press "Command + Shift + R" (Mac) Clear the Cache and remove the Cookies for websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences). "Remove the Cookies" for websites that cause problems: *Options/Preferences -> Privacy & Security<br>Cookies and Site Data: "Manage Data" "Clear the Cache": *Options/Preferences -> Privacy & Security<br>Cookies and Site Data -> Clear Data -> Cached Web Content: Clear Start Firefox in <u>Safe Mode</u> to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if <u>hardware acceleration</u> is causing the problem. *switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes *do NOT click the "Refresh Firefox" button on the Safe Mode start window *https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode *https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems