Being remote tech, and often unsupervised, this sort of thing is not easy to track. It is demanding of a 'system of perfection' and such a system can never exist. Seriously suggest several work arounds, like supplementary quizzes, Lessons based on each section of the documents or videos. The other issue is that if videos are too long, i.e. more than about 6 minutes, students will get bored and close them, not bothering to complete them. I would suggest that videos be short and have one and only one point. If a topic can't be broken down into small chunks then the manner in which that topic is being addressed needs to change. Similarly with associated documentation, that too should relate only the the point of the video. If a point of a topic can't be discussed in one video, then divide it into smaller chunks with quizzes relating to that chunk. If a teacher can't do this, then find someone who can. I can think of single topics that have be spread over entire semesters, but still have so many individual points that allow for such chunking. Also, students can gain a far more detailed understanding of a topic if presented like this, believe me, they get to understand individual points, not have them blur into others. Good luck.
