I don't know if there are any videos out there specifically for teaching younger kids to play. At 12, even for a new player, they are just about ready to learn the same things as an adult would.
One thing that you absolutely should work on with him is proper fundamentals, good stance, good straight stoke, follow through, staying down on the shot till it's done. Also something that I really wish I knew more about, proper alignment of the head/eyes over the cue to aim that shows him a clear picture of what is really on the table. It took me about 20 years to realize I needed to shift my head 1/2 inch to the right to stop missing many shots I used to miss and I am also working on this same thing with my son who is 14 and misses a lot of shots from a certain angle. He just does not line up properly with the shot.
I think the Jeanette Lee video is geared towards beginners (she may have more than one but maybe not) and what boy would not want her teaching them to play

.
Mike Immonen's video is also good, I have only seen clips but they are very well described and taped. He has a 3 parter, beginning tape, intermediate and advanced.
As above, Jerry's video is said to be one of the best, and I've seen him work first hand with kids at the Junior Nationals a few years ago. You can probably find used copies around. I have a VHS of his older video but I have not seen that in a while or I'd send that to you.