Live chess or over-the-board event in person, then yes this is probably cheating to watch this video mid-game. If correspondence/chess.com Daily chess, then no it isn't cheating. As long as the source (video, opening database, book etc.) does not have engine evaluations, then you are fine.
Obviously, in-person over-the-board is most strict, then live chess and Daily is the most flexible.
I evaluated a chess position with the help of seeing this video : https://www.youtube.com/watch?v=3su1RGtmfcw
Is it cheating? I didnt used any engines ect.
But still some people are still saying I am CHEATING