Try disable the Hardware Acceleration:

Try disabling graphics hardware acceleration. Since this feature was added to Firefox, it has gradually improved, but there still are a few glitches.

You might need to restart Firefox in order for this to take effect, so save all work first (e.g., mail you are composing, online documents you're editing, etc.).

Then perform these steps:

• Click the orange Firefox button at the top left, then select the "Options" button, or, if there is no Firefox button at the top, go to Tools > Options.
• In the Firefox options window click the Advanced tab, then select "General".
• In the settings list, you should find the Use hardware acceleration when available checkbox. Uncheck this checkbox.
• Now, restart Firefox and see if the problems persist.

Additionally, please check for updates for your graphics driver by following the steps mentioned in the following Knowledge base articles:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

• Upgrade your graphics drivers to use hardware acceleration and WebGL

Did this fix your problems? Please report back to us!

Thank you.

If you right-click the video area, do you get a Firefox right-click menu or the Adobe Flash Player right-click menu? If it's a Firefox menu, you may have opted in to the HTML5 trial and the troubleshooting steps would be different than for the Flash player.

About the HTML5 trial: https://www.youtube.com/html5

Hi, there! Thanx for info, but it wasnt't unfortunately that. Greets Dogfish

Try reduce the resolution:

• Reduce Resolution

You might also want to disable the Flash Player plugin's use of hardware acceleration, which is an independent setting. See:

• Adobe support article from Adobe: http://helpx.adobe.com/flash-player/kb/video-playback-issues.html#main_Solve_video_playback_issues

• Lifehacker article: http://lifehacker.com/5796783/fix-a-green-screen-on-flash-videos-by-disabling-hardware-acceleration