Yes - just imagine - full forward cyclic, losing height quite quickly; 90 deg nose down, really going down quick now; inverted but still going down very very fast, where did that 1000 feet go? Not to mention the negative 'G' and the fact that both the engines would have been starved of oil and blown up.
I suspect that the Red Bull pilot will do it from a high rate of vertical climb or from climbing backwards flight. Good luck
Back to the flip, so to speak, I believe it was GW and others who started off doing a version of the manoeuvre to get from the high hover (NI Ops) down to low level quickly, a sort of 'over the shoulder' transition. Then it was a case of well if it will do that, will it do this? and the back flip was born.