If you only buy one tape you will be disappointed because each tape is basically a one hour lesson dealing with one issue. He shows or sets up a drill and has a player or himself shoot it over and over. He will point out the mistakes made and how to correct them.
His first tape "60 minute workout" can stand alone but I think that Bob Henning's Pro series is better (
http://www.bebobpublishing.com/mainindex.htm) as he does the same shots and condenses them. There are a few others such as the hustle tape or safeties that can also stand alone.
I tapes 1 thru 55 because of the better deal by buying in volume. There are a few stinkers in there. Having that series I can see the benefit of having them because address stuff from previous tapes.
There is a lot of good info but do not expect to learn everything about pool from one of his tapes. Most of his tapes expect you to know the basics. To learn that I would recommend taking lessons from one of the BCA instructors.
Are they worth the money? Only if you are willing to spend the time practicing what he wants you to do. 55 tapes will take 55 hours of viewing. Then in each tape he claims that you will improve if you practice it for anywhere from 1 to 8 weeks. Even if you practiced each tape for one week it will take more than a year to go thru them. I think he now has close to 70 tapes.