Hey man, always happy to see people willing to teach the game. I'll look over stuff and comment.
1st video: Perhaps too late for critiques, but woo boy. You threw a lot at someone who has never heard of the game before, and really talked about a lot of things I don't think you needed to to make the game make sense.
In my experience teaching new players, a lot of the flow of the game is incredibly confusing to them, until they see it in action. Once they rolled a few attacks they generally (though not always) figure it out. So talking about rolling the dice in combat, or Save DCs, even as briefly as you do, might be too much for people.
Good segue into the things I have found the hardest to deal with when teaching new people.
Character creation is a nightmare for new players. Figuring out their modifiers, understanding their choices, choosing anything. It really comes down to "analysis paralysis". 5e is much better than some of the older editions, but there is still a lot for people to go through without understanding the rules yet. Unlike in your video series, Character Creation is generally the first thing most new players end up doing, so they don't have context for the craziness of the system.
As a corollary of that, the bonuses to the rolls and which dice to roll seem to confuse people for a while. I've had people combine all sorts of numbers in all sorts of ways, and rarely are they correct for the first few sessions.
Other than that, it is generally a struggle to get people to take actions in the game. New people are generally (but not always) shy about speaking up and doing things, and they will often make silly decisions because they are copying something a different player did. The idea of being capable of doing anything, of interacting with an imaginary world that responds to what you do, it's incredibly hard to wrap your head around.
The problem with these things, is that they can't be taught effectively. They have to be seen or experienced. Players generally pick it up fairly quickly, but it's a rough learning curve to get over.
Don't have time for the second video right this moment, but hopefully I was somewhat useful and not an entire downer.
