Day 2 was core and cardio in MBF, and the 15-minute cardio (modified again with a few different moves) from 645.
The MBF workout is interesting. You do three blocks of cardio (each block including two exercises) separated by four blocks of core work (each block including 2-3 exercises). Each exercise in the cardio blocks is done for three rounds, again with no rest between the moves. Each exercise in the core blocks is performed for two rounds, with no rest between the moves. And, there is no rest between the blocks (aside from the time it takes Megan to show the moves in the next block), so you essentially do three rounds of your two cardio moves, immediately transition to the core block, do two rounds of those moves, immediately transition to the second cardio block, etc.
At the end of all that, you do have a four-minute AMRAP block. AMRAP stands for "as many rounds as possible." In those four minutes, you do four reps of three of the cardio exercises and then 20 jump rope reps, which counts as one round. You rest a few seconds to catch your breath and then do another round. The goal, as it sounds, is to do as many rounds as you can in that four minutes.
The workout is good and goes by very quickly, but it is hard. Having zero rest time between exercises and very little rest between the blocks is tough. Throughout the workout, the various cast members (who all vary in their fitness level and ages) take unscheduled pauses here and there. Even if you are in fairly good shape it will be a challenging workout.