Wow big question... depends on what you need!! There are tons of great channels and videos out there. I would recommend spending some time finding channels you like the hosts for but here are some ones to get you started.
These are the main ones I watch. I find that the host's are knowledgeable and all have multiple years in the industry. For many of them if they dont know something they say so, and if they are responding to a question they can usually cite a source.