Please, for the love of all things good, script these videos.

Sit down and write out what it would be like to talk to an adult about what you're introducing, and articulate the best possible educational explanations of what, how, where, why and when.

Not only will the videos be shorter, they'll be super useful, from beginning to end, and you'll be able to add bookmarks to the different time sections, like having paragraphs in a script.

See loopop's videos for an example of how this can be done.

Anything less than this is atrocious misuse of everyone's time and energy, and suboptimal to the point of being tragic.