I haven’t seen his videos, but I have most of Charlie Francis’s books. While very good for learning about how to train for the 100 meters and raw speed in general, I don’t think they are that helpful for a new track coach.
I think the majority of high school athletes can show the most improvement in the widest range of events (100 meters up to 600 meters) by focusing on speed endurance, something that is not a big part of the Charlie Francis system since he trains 100 meter sprinters.
If you don’t have it already, I’d recommend the USA Track and Field Coaching Manual for a good overview of all the events. It goes into enough detail in explaining each event so you would be able to teach someone else. However, the training/conditioning sections for each event aren’t that great.