I have several Ellen Barrett workouts in my collection. She's a good instructor: her workouts are well-designed; and her demeanor is cheerful and encouraging without being over the top. Pick Your Level Weight Loss Pilates (2006) is not one of the DVDs in my own collection, but I recently rented it to give it a go.
The full workout runs 30 minutes, though you can choose to do it in 10-minute segments (standing, side-lying, or mat). Throughout the DVD, there are 3 different workout options (demonstrated by Ellen at level 2 and her assistants at levels 1 and 3).
While I found the 3-level format distracting at times, and while I do feel that the instructor should be the one to do the level 3, generally speaking I did like this workout. For a half hour workout, it's very thorough, and it proceeds at a good pace without ever feeling rushed. And Ellen always has a few moves or variations you don't see elsewhere, which helps prevent workout boredom from setting in.
Ellen Barrett has a website and a blog, and a new DVD coming out this fall.