Up until what level do you intend to teach the language? Only introductory - common phrases that tourists can use - or more involved, i.e. actual grammar/kanji? If introductory, there are already tons of channels that to this (e.g. JapanesePod101, Discover Japan). If you're intending to produce an actual textbook alternative, going from zero to beginner/intermediate, you should keep in mind that videos are not very suitable for learning. They prevent the user from going at their own pace - you can read text as fast or as slow as you want, but if a video is going too fast or too slow for you, there's nothing you can do about it. Plus, rewinding a video to repeat something you didn't understand, or even finding back a specific point in time in a video that you watched before, is harder than re-reading a sentence or finding back a passage in a textbook.