Below, check out a video of a complete Dimebag Darrell clinic that took place June 3, 1993, in Arlington, Texas.
The Randall Amplifiers-sponsored clinic, which is basically a Q&A session (where Dime is practically begging the subdued crowd for questions—very hard to believe in retrospect), also features some fine shredding by Darrell.
The entire video is about an hour long. Note that the sound isn't great; it's a bit muffled, and you'll probably want to raise your volume considerably, as I just did.
By the way, there IS an official Dimebag Darrell website, and you'll find it right here. Enjoy!