TAS is a Tool assisted program/speedrun for various games. Certain TAS comes with a disc or computer emulating enabled that can do things that are deemed incredibly hard or deemed impossible. I posted a video with DMC3 and Capcom vs SNK 2 in the media library.
Chapter 4 and 2 others has a loop in there that is completely random but he managed to get it in 1 shot, there's a certain delay of FPS to tell whether he is using TAS or not. It "Is" possible to do a no damage run but the ways I've seen it were the same and more logical compared to the one posted on that review.
@Fiend Busa - Can likely explain it since he's likely attempted a No damage run for NGII. Basically there's certain ones where you have to avoid damage but the guy basically bypassed damage with loops every single time which is extremely rare.