One example I can think of is in "Panic Attack", during the solo section - MP is playing the bass drum at constant 16th notes, and in one moment he is playing in 4/4, the tempo feels slow, but then it shifts into 6/8, with the same 16th note bass pulse. The groupings change from 4 to 3, in that instance, and so the tempo "changes" and feels faster.
Looks like they're doing something similar here. It's amazing that MM is actually taking the time to calculate BPM, which means he's obviously trying to nail some drum part(s) that require knowing exactly how fast that part of the song is going to be.
-Marc.