I do have Sorenson Squeeze to capture video on but that has the same problem. I just did a restart and I was able to capture a tape. Once I did another one, VidCap came up with the same error message.
I did install DivX for Windows on my computer 2 weeks ago (and I was at this event all week long last week) so maybe that could be corrupting it? I’ll uninstall DivX, restart the computer, and see what it does.