11.8.800.94 IE9 plays some videos but not all, FF does

Win 7  64, ie 9. ff 22.0 also at 11.8.800.94. Video cards are Nvidea 6200 DVI and 8400GS. All software & drivers are current. This is a Gigabyte MB, 4GB.   

IE will play some youtube videos like this one.http://www.youtube.com/user/UFCselect?v=DkYDh4WFnCg

But it won't play https://www.youtube.com/watch?v=VSQXZhGEHYs

Sometimes the leadin commercial plays, but the video doesn't.  

The second video starts but stops immediately. Eventually it times out.  There is a leadin commercial &

maybe the problem is related to that.  This one acts the same way. https://www.youtube.com/watch?v=DhmoaVu3ZN0

All those videos play fine on FF.

This NBC video plays on both IE & FF.

http://usnews.nbcnews.com/_news/2013/07/16/19503222-lapd-chief-to-violent-zimmerman-protesters-you-come-here-again-tonight-you-will-go-to-jail?lite  

all HULU videos I tested worked on both. http://www.hulu.com/#!watch/511186  as a sample. 

Hardware optimization doesn't change the symptoms, data and storage have both been deleted.

I tried using both video cards & that didn't make a difference.  

the Gremlins strike again