Hi motiniva- Youtube videos should work with the latest flash player. Just to be sure you can check your flash player here: [http://www.mozilla.org/en-US/plugincheck/ plugin check] If it's not flash, try getting rid of everything that [https://support.mozilla.com/en-US/kb/Clear%20Recent%20History#w_how-do-i-remove-a-single-website-from-my-history Firefox has stored for that website.] You should also make sure you are on [http://www.mozilla.org/en-US/firefox/new/ the latest version of Firefox.] Hope that helps!