One of my favorite Bitcoin content creators of all times: Ioni Appleberg! here is his Youtube channel. One of the best of the best! https://www.youtube.com/user/waem/videos
Then we have the old series "101 blackboard Bitcoin": https://www.youtube.com/playlist?list=PLzctEq7iZD-7-DgJM604zsndMapn9ff6q
If you miss these 3... anything else is meaningless.