Yeah, I would say that sounds about right. They're starting in octopus half, a variant of backstep half, and there are only a couple of legit sweeps from there. The most basic just rolls you over into topside half, so it's kind of a 50/50 position. I don't think black really has the bump sweep to begin with, but he's about to lose position anyways if he doesn't go for it because blue nearly has the leg clear. Usually you just kind of shoulder roll while keeping your legs locked, but blue's posture is so low that he has to break the half guard in an attempt to gather momentum. It's hard to say for sure but I believe it's black who tries to pivot and re-place his right leg into backstep half position. If he doesn't then he's at risk of leg entanglements. Taking the back from an attempted backstep isn't that uncommon but I think usually you're blocking the leg that they're stepping back with. It's super cool that he indirectly blocks the backstep by elevatoring the planted leg. I wonder to what extent Giles developed this technique because of his expertise in leglocks, because by hooking the inside leg like that you're pre-emptively defending saddle entries as well.