The principle is simple, really, and probably works quite well!

I was classically trained for a couple of years and was taught to have my thumb anchored in the centre of the neck, which of course gives the fingers something to press against when barrčing... it also means that your fingering hand is - for all intents and purposes - "floating" over the strings, which does make playing the G and C shape barre chords, as well as the various augmented, diminished and weirdo #9b7 type chords with movable shapes really quite easy.

However, as I got older I got lazier and - amongst other guitar playing sins - started hanging my thumb over the board, especially when playing power chords and now find that, while still not terrifically hard, the barre chords and wierdo chords are not as easy to play as they were when I was playing correctly from a technical point of view!

I don't have "Steve Vai" fingers but I am blessed with very strong hands, which to a certain extent can cover a lack of proper technique, but stll....

If that video makes playing easier, then kudos: it will, however, still take much practice and a mindset that can adjust to new and better ways of doing things!!