either this guy has superhuman reflexes or he has practised his ass off cause controlling the character in this game is not a joke and this is one of the hardest game for a speedrun only because of how slippery the character movement is
This video is what is known as a Tool-Assisted Speedrun (TAS for short). For TASes, games are slowed down or played frame-by-frame (usually alongside memory viewers for extra stats) to craft a theoretical perfect run of said game (at least with the current knowledge and research of the game in question). These are not human runs, nor are they trying to advertise themselves as such, but they are a showcase of just how far you can push games. That's not to say that all techniques shown aren't possible in RTA runs, but there are a group of techniques that are deemed "TAS-only" due to their insane degree of difficulty. There's still an incentive to get a faster time within TAS communities, but TASes are more of a collective effort than a pure competition, due to the pool of research put into many of these games.
I don't understand why you are ending the levels with more than one health. There is several spots you could have taken damage And been boosted further along, which would avoid the time it takes for health to count down at level end