But then, anyone can easily beat a woodpusher who specializes in the French defense: By simply playing 1.Na3.
Nobody has yet become a Grandmaster by watching chess videos... True or False?

Clearly false.
Just yesterday my niece's 5 year old daughter was crying, so we put a chess video in front of her and left the room.
After some time when we went into the room again, we found her to be a full fledged grandmaster. She had started beating Anand - I mean, really thrashing.
PS:
My niece was quick to admonish her daughter, "you naughty girl, stop hitting your 2 year old kid brother".
I don't really look at chess.com videos but youtube videos, videos have helped me tremendously and how to open up but I really look at various games played by grandmasters. At my local chess club I beaten a guy that specializes in the french defense and because of videos in the french defense I was able to beat him.