isight messing w/ itunes video playback?

I have another problem with iTunes video playback and the cloud, which I've posted elsewhere But then, there's this one too. I found our old iSight webcam today and plugged it in to our Mac Mini, via a firewire port on an attached external hard drive.

The camera works, as in I can see video, however it seems like it's interfering with movie playback in iTunes. That is, when I try to play DRM protected movies with the iSight attached, it seems to stall the video playback or stop it.

To note, I also have the problem where when I have Remote Desktop running, the video playback from iTunes on the monitored Mini is only in checkerboard... which fixes itself when I turn off Remote monitoring. But this is in addition to, not concurrent with, the problem of playback with the iSight connected.