I haven't found anyone who's purchased the FitTV ones to verify. But on the Discovery Store web site, they offer these. The descriptions for each DVD says they include 3 20-minute workouts. So my guess is that Stretch Max would be the same as Cathe's. Core Max is the same, but no premixes. And Low Max is anyone's guess - perhaps each workout is only 2 intervals (leaving out one of the original intervals).
The price is great for the set of three on the web (44.95, I think). But I always am skeptical - you get what you pay for! Now that you have seen them at an actual brick-and-mortar store, maybe someone will purchase them and let us know.
Diane