I see nothing wrong with tape training providing that you DO go out and either attend seminars or receive private/semi-private or group instruction from time to time.

Regarding BJJ, etc (any alive art), you're going to eventually "test" everything in application. You'll know if you're doing it wrong basically.

Checking out tapes or DVDs is a great way to supplement your training, particularly if you've already got some 'game'.

For example (and I'm sure other experienced guys are the same way), I can be watching a FIGHT (not even an instructional video), see a move and immediately understand how to do it and, how to put it into my own game. Considering that most fight moves are "basic" anyway, that isn't incredibly difficult to do.