Depends on what you are looking for. If you want the usual basic technics for quick tabletop paintjobs there is plenty you could find for free on youtube without the need to spend money in a dvd.
If you want to go the extra mile in your painting be carefull in what you buy. I don't own any dvds so I can't give a proper review...
... but, if I was going to buy one, this one would be right there in the top:
Painting Miniatures with JBT, available from Kraken Editions. Seems that the multi-language DVD is out of stock though and its only available in french for the moment.
Its from Jeremie Bonamant, one of the best painters you can find!