It’s actually pretty interesting to see not only the struggle to get it completely alternate picked and how technique can fall apart with speed under slow motion camera with the Magnet (even though Ben is pretty good at alternate picking in general). But you also see him try other ways to find a compromise between not playing it with full alternate picking and still having it sound “right”, by trying to mix alternate picking with pull-offs after trying to incorporate sweeps.
And it’s still a bloody hard piece of work. The tempo is 209BPM with 8th note triplets, so around 10.45 notes a second if my math is correct (equivalent to 156ish 16th notes). I wonder if or how you can build the stamina (not just physically, but nervously and mentally) to play it: I’m pretty sure some players can get a couple bars at speed, but the form can break down when alternate picking that fast for any longer period of time, nevermind a whole solo or a whole song!