I think the jury will be out on this indefinitely, but don't underestimate the Russian airshow guys. They are both very talented and utterly insane. If they want to do a pass at 8 feet, they'll probably be able to.
Evidence: To me the biggest factor is the location of the missing gear, which would be off the pavement. The AOA issue is a non-factor, at 400 to 500 knots, any AOA is going to be miniscule. The AOA vs airspeed is not a linear curve, and at any higher speed, it's going to be quite flat. The stabilator position argument is irrelevant until we know more about this particular platform. Heat plume: the velocity (say 500 knots) will contribute to a reduced plume. the huge plume you see even at idle is due to a lot of exhaust gathering in a high concentration due to the slow speed. I think at high speeds, it's going to be pretty diluted. If he's at 500 knots, at sea level, those throttles are nowhere close to military, they're probably well back from the detent. Nozzles: Big time evidence for real photo. They are closed, indicating some throttle setting well above idle, but below afterburner.
All this is pure opinion, of course. I think it's real.
The guy in back may be voicing a RA to the pilot in front. As you fly this low, this fast, your focus tunnels more and more forward rather than down. His ability to look inside is zero, hence a guy in back saying "8 feet... 7.... 8..." etc would work, or maybe the RA is auto-voiced.
Good thing for us that the MiG and Sukhoi design bureaus were both well behind the west in electronics, sensors, and avionics, because their airframe and powerplant technology is every bit as good as ours, probably better.
