Reduce the resolution until you're right on the edge of usefulness, then reduce the frame rate until you can barely stand it. Then play with the encoder settings until it keeps up.
Even so, don't get your hopes too high. I had a laptop that I used with an NTSC camera (640x480) to record a bread machine running, so I could catch it acting up. Canvas and output size were set to that too, to keep it from scaling anything, and I *still* had to turn it down to 10fps before it would keep up.
That was fine for the bread machine, but are you sure that "analog TV quality" with less than half/quarter of the original TV frame rate (depending on how you count interlaced frames), would be useful to you?
