I want to try video sensing while running Firefox 21.0 on Ubuntu 13.04. Can anyone recommend a compatible camera that will work out of the box?

Thanks.

Answering my own question - I bought a Microsoft VX-800 and it works. In order to work with the video sensing projects, I needed to invoke the program
gstreamer-properties
from the command line, go to the Video tab and set the device on the bottom of the dialog box to my camera. The camera works with other applications without taking this extra step, but would not work with Scratch 2.0 in the web browser until I did that.

LOL