If you are already committed to sending video data to a computer, would it work for you to connect a web-cam camera to the computer directly, trim the data into the useful info and send it to the arduino? I suppose this all depends on the application, but I have created a project with the arduino with this arrangement for a real-time image tracking system.
What are you trying to do? With a bit more info we may find that it is not needed to connect a video stream directly to the arduino.
salernos