What's wrong with that video? I think it's an excellent of example of what you can do with this game and how to make the mechanics work to maximum advantage for you. A couple of things in there I hadn't thought of yet. Good stuff. Cheers.
It perfectly show how bad, silly and/or cheesy the combats mechanics are in a supposed D&D game
That's not how I saw it. Alot of thought and a deep understanding of the games combat mechanics went into developing those tactics. By what metric are you decreeing them silly or cheesy? I mean he isn't just throwing barrels around and lighting them up.
He's making use of many different mechanics simultaneously and using them in the most advantageous manner, including maneuver, surprise, advantage, positioning, his own action economy, dipping, etc etc. I mean, it might not be your thing, but I don't see how you can deny the guy knows what he's doing with the game, and how to make the most of it.