I would first recommend to disable one of the video players to see if this might be causing the issue. Second I would recommend: *[[Upgrade your graphics drivers to use hardware acceleration and WebGL]] If its Flash player try: Some problems with Flash video playback can be resolved by disabling hardware acceleration in your Flash Player settings. (See [[Flash Plugin - Keep it up to date and troubleshoot problems|this article]] for more information on using the Flash plugin in Firefox). To disable hardware acceleration in Flash Player: #Go to this [http://helpx.adobe.com/flash-player/kb/video-playback-issues.html#main_Solve_video_playback_issues Adobe Flash Player Help page]. #Right-click on the Flash Player logo on that page. #Click on '''Settings''' in the context menu. The Adobe Flash Player Settings screen will open. # Click on the icon at the bottom-left of the Adobe Flash Player Settings window to open the Display panel. <br/> <br/>[[Image:fpSettings1.PNG]] <br/> # Remove the check mark from '''Enable hardware acceleration'''. # Click '''Close''' to close the Adobe Flash Player Settings Window. # Restart Firefox. This [http://www.adobe.com/support/documentation/en/flashplayer/help/help01.html Flash Player Help - Display Settings page] has more information on Flash Player hardware acceleration, if you're interested. Does this solve the problem? Let us know.