I have researched this problem. CLICK ON THIS LINK.
http://forums.comcast.com/t5/XfinityTV-Website/Video-cannot-play/m-p/2115074#M32308
I have researched this problem. CLICK ON THIS LINK.
http://forums.comcast.com/t5/XfinityTV-Website/Video-cannot-play/m-p/2115074#M32308