I'm looking for a video capture board that works in Ubuntu without a lot of painful configuration or hassles.
I'm looking for an external USB-2.0 based capture board and I would prefer one with an onboard MPEG-encoder.
Hauppauge HD-PVR solves your problem if you're dealing with analog video. It works as V4L2 device with USB interface.
The list of supported chipsets is at http://www.exploits.org/v4l/ Anything that uses one of those video chips will work.