Based off of what?

He pulls it out and loads it the way he does like a normal gun at 0:05 with a mag into the magwell. The slide kicks back with every shot, then locks back on the last shot at 0:12. It's dark and the gun is small, but there's nothing in the video that makes it obviously clear it's a toy (orange cap) or adapted to firing blanks (blue barrel) either.

Nothing about this screams that it obviously is just a toy whereas it behaves the same way a real firearm would.

I've been shooting for a decade now and I've never seen a toy that behaves this way. He either has a blank-firing gun (still incredibly stupid to shoot in a public space regardless) or he was dumb enough to shoot off a real gun.