Sorry for not making a response to 185107; CLSID_VfwCapture is kind of an awkward situation and I wasn't sure how I wanted to proceed with it...
The problem is that we kind of roll into one filter what should really be two (and the bulk of neither of which should be implemented in qcap, but that's a problem for another day).
In practice I have yet to see a video camera exposed through the VFW capture filter on Windows. Accordingly I'm inclined to just get rid of any VFW-specific code or tests (at least, if it starts causing problems, like here—obviously we still need to keep the IPersistPropertyBag bits around, though...)
I've sent a patch effecting this.