The workout blender is a cool concept, but the reality isn't quite as cool...
To answer your question, on the Timesaver DVD, you can use the blender only within each individual workout. You can blend various segments of workout 1 in a different order, but you can't blend parts of workout one with any of the other workouts.
That is the big disappointment with the Blender feature as SNM uses it. First, you can only blend parts of individual workouts on a multi-workout DVD; second, you can only blend a total of 5 or 6 parts, and SNM decides which chapters make up those parts.
In other words, the blender would be so cool if you could mix parts of Supersets with PushPull, but you can't. (However, the premixes pretty much cover anything you'd want to blend, anyway.)
If SNM brings the blender back, I hope they cut down on premixes (in quantity and quality of premixes, go back to Intensity Series level) and let us blend portions of two different workouts together. Of course, if they continue to put only one workout on each disc, that's not happening!
Sorry for the long response

Hope I answered your question!
Wendy