Windows 7: Mouse movement causing jerky video in IE9

If I'm on YouTube or IMDB watching a trailer -- ANY streaming video whatsoever in IE9, if I move the mouse at all, the video jerks. I've tried launching IE9 with no add-ons, safe mode, everything. This doesn't happen in latest Firefox or Chrome or Opera, ONLY IE9. I've tried with wired USB mouse AND wireless mouse with same results. CPU usage does go up to way higher than it does in FF or Chrome or Opera from mouse movements (40%-50%) but I don't think it should be so high as to cause jerky video playback (sound is not affected, by the way -- only video). Already have latest driver for my ATI graphics card so that can't be it.

See video here to see what I mean: capture 1 - YouTube



Any help would be greatly appreciated -- thanks in advance!!

What kind of display are you plugged into?
That sounds similar to what happens when you are using trumotion or some other lcd tv feature with a computer hooked up to it.
Of course that would only be the case if you had the system plugged into a tv.

I'm actually plugged into a Samsung LCD monitor via DVI----BUT I'm also connected to my LCD TV in my living room via 50ft HDMI cable thanks to HDMI port on my graphics card. Big fan of WMC.
But this happen when that TV isn't even on, which is the case whenever I'm at working at my PC.

Could that be the problem?

no, that kind of rules out my theory.