Yes, I borrowed a webcam (intel CS110) and even though I see the video with Kopete's configure tab, I can't seem to send the video (or the other end can't receive, I don't know which).
Both sides are using KDE 3.5 (Kopete 0.11), 3.4 is not even installed on the systems in question so it is not a library mixup with KDE. The protocol is MSN, I have not tried yahoo yet.
I see the exact same behavior. I select send webcam, the popup appers on the other end, but nothing when "accept" is pushed. The same when the other end asks for my webcam and I approve.
Also, the webcam settings don't seem to be saved after the configure window closes. Specifically, this cam need the auto contrast and auto color, but it reverts after the window closes.