Damn, that video is amazing. Looks like they pretty much zeroed out the velocity, but cut the engines before they zeroed out the altitude. Best of luck to Deep Blue Aerospace on their next test! Looking forward to the first orbital flights of Nebula-1.
I wonder if the engine cutoff is done manually or what kind of sensors turn it off. I would think maybe some sort of pressure sensor on those stability arms or something would indicate the rockets actually on the pad before turning off the engines maybe. Perhaps some sort of back draft would trigger that though if it's too sensitive or the threshold is too low. Or maybe sensors built into the landing pad itself that signal to the rocket.