Instead of buying the course, get some lessons from a good coach.
If you have to, I would pick the cheapest teacher and I think will be totally ok.
Maybe it can be useful because you need to improve your studying method, I cannot see any other reason.
Need to play with someone stronger: play with stockfish,
Need to spot your mistakes: analyze your games,
Need to learn some tricks: there are plenty of them for free.
Is there a problem or two that are recurrent in your games when you analyze them?
If you cannot find one, ask the community, your friend, another friend or a coach to find it with you.
I'd be very surprised to hear that a GM video helped you find what was precisisly blocking you at this moment.
