I sent a report about that yesterday (not realizing it was a known bug). The problem is not really with Channel 9 IMVHO. WMP9 for Mac has a LOT of bugs (check the Mac WMP newsgroup :-> ) and this is one of them. You'll have the same problem in all web browser that support the WMP plug-in like IE, the Mozilla-based browsers or OmniWeb 5.0b5.
As a workaround, you can: