We can't help you unless you provide more details. Which videos on which sites? Are you using any extensions which could be contributing to the issue? Do the sites you use require Adobe Flash Player?

If you have problems with current Shockwave Flash plugin versions then check this: * see if there are updates for your graphics drive drivers '''https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration''' * disable protected mode in the Flash plugin (Flash 11.3+ on Windows Vista and later) '''https://forums.adobe.com/message/4468493#TemporaryWorkaround''' * disable hardware acceleration in the Flash plugin '''https://forums.adobe.com/thread/891337''' See also: * '''http://kb.mozillazine.org/Flash#Troubleshooting'''