I actually own a book called "How to Sound Intelligent in Japanese". It teaches you all the technical words.
I find it hard to believe that videotaping the opposing coach is considered scandalous! I had no idea there was any sort of gentlemen's agreement that one wouldn't try to break the other team's code. I figured that was part of the game, and ditto baseball.
I figured it would be of limited use anyway, since coaches don't, I'd think, call every single play, but leave things to the judgement of their QBs and defensive captains. (And catchers/pitchers, accordingly-- though it seems the outfield only needs to be briefed as to where to move to on a per-batter basis.)
I don't see taping the coach is radically different than taping the game and deducing the other team's playbook. As you suggest, though, I think intercepting the radio communications would be out of bounds.
I note that some of the more premium internet services related to NASCAR can give the viewer things like the in-car radio; obviously it wouldn't pay for a team to hire guys to listen to the other 43 cars in a Nextel race and try to produce useful info in a timely relevant fashion, but I do wonder if anyone works on that sort of thing.
NASCAR radio traffic (at least between the driver and the team) is in the clear. (And they are asked to keep their language clean since anyone could be listening in.) I rented a scanner for one race, and there's actually very little chatter.
I'm sure that there is some team code for specific situations where they don't want other teams to know what they are about to do (i.e. leader coming into the pits during a late caution), but in most cases whatever is discussed won't change the other drivers decisions or behaviour.