So i have my PC connected to TV (42pfl4047t) via HDMI.

I watch a video stream with firefox on my PC and its great, but i want to watch it on my TV.
So i drag firefox into TV screen and the video plays very jerkily.
Like it was with wrong FPS settings or something.
From TV settings i used PC mode on and aspect ratio original.

Is there any other option that might help?

Also the same effect happens when i view any other video that way.
Including watching movies with XBMC, however from XBMC settings i enabled "Sync playback to display" and the problem is gone.

Any ideas?