They seem to really be moving, maybe 50, maybe more? Getting entangled with each other, and having a partial collapse, right before going over a precipice, would be my main concern. Even more impressive they are confident and skilled enough to do that in such close formation.

I would REALLY like to fly with them, tag along behind, one notch of flaps, my speed would be similar if not slower. Couldn't make all those tight descending turns but for sure could leave a lot of the tracks they were leaving, damn that'd be fun, but I want a fixed airfoil! Great camera work also, that whole production didn't just happen I'm guessing, that took some planning