For those times when you can't make it to class a DVD at home is better than nothing at all. While nothing can really replace the touch of a live teacher, the Pilates Intermediate Mat Workout by Gaiam is a pretty good substitute.
As you can surely tell by the name, this DVD is not meant for the beginner. This is a solidly intermediate workout that builds on the material taught in the Pilates Beginning DVD. Ana Caban teaches the class and she provides clear instructions and cues throughout the exercise. Modifications are shown by another "exerciser" although not as with much frequency as the beginning level DVD.
These intermediate variations are more intense and the pace a bit more challenging. Geared to the intermediate level student the exercises flow into one another and are not bogged down with a lot of instruction (another reason why this is not a good DVD for beginners). The workout runs about 40 minutes, with a 13 minute bonus Energy Boost Workout which is short but intense and targets the abs in a great way. The scenery alone will energize you - it is filmed on location at a tropical beach.
Buy the DVD for $15 from Amazon.