are u using the correct references
use the 900 references for ALL DX .. in ur project
reason so MS tried to be i dunno ... ****????**
the summer update 9.0B (901 references) does not contain support for hte video hence that could be a reason y ur video is not able to work properly only the 9.0A SDK works.. n now u can no longer dl it..
its not ur code i guess.
but den again if u revert to 900 there wld be a lot of problems in ur code.. sooner or later..
Hope MS comes out with the 901 reference for video...