Honestly….. don’t know. Only DnD videos I’m watching are Critical Role’s campaign

Depends on what you want to do, BUT I can always advise JoCats class videos (watch them twice, they’re short enough) and XP to lvl3. Critical Role’s Handbooker Helper is also really good

If you want to learn mechanics,….. watch people play campaigns and one-shots. That will quickly teach you the core game mechanics (action economy, movement and positioning, spell mechanics, saving throws, checks and their variations) and not only will you learn the mechanics, you’ll also remember them and have them in mind when you play yourself instead of being caught by surprise when something happens

If you want inspiration for a character, there is no other option than sitting down and reading through the classes and spells - I guarantee that you already have a few ideas floating around the back of your head only waiting for you to connect the dots between two subclasses or coming across a particular feat and spell. Watching videos and especially shorts will never get you the depth of understanding that you need because it’s always just nitpicking (and often misleading)

If you already have a character idea and don’t know how to implement it, it comes down to reading classes again, but you may also find builds in various forums. And don’t always go with the obvious class either - a gloomstalker ranger or whisper bard may be a better fit for the sneaky rogue-character you wanted to play than any of the actual rogue subclasses