I didn't have the sound on (courtesy reasons) but I wonder why he sealed the shot cup to the slug in front?

The way I reason it, the shotcup is not going to separate from the slug after it leaves the barrel. . . If it was me, I would have either pried open the crimp and resealed it later with wax, or cut off the crimp closer to the case mouth, cut back the shot cup petals and put a roll crimp on. Not that I have ever done a roll crimp. The way he sealed it in my opinion, there is now no crimp for the round, so the 'start pressure' is going to be erratic.
I am going to have to try this modification though to see if his way is good or not.