I've had a couple days to recover and given that I now know what to expect, I decided to do 1+2=3 again today. Knowing what's coming (and when to put cushion under my knees) made a big difference but it was still sweat-fest hard!
I still had to take a couple of breaks to catch my breath and in some spots go slower in others to regain my composure. It's also like many barre workouts in that it seems to get harder in a way, because once you know the sequence, you start perfecting your form, and that can make it more intense!
My current goal is indeed to master this workout, so I'm going to attempt it once a week for now, trying her other workouts on one day a week, and doing Cathe the rest of the time!