I'm not a professional, but last year I made a few videos for conferences about math.
For a 15 minutes talk, I had to film each "slide" like 4 or 5 times, and then glue them together. It was like 4 hours making the video and 4 hours editing, to get a (not professional) 15 minutes talk.
I'm not sure about videos of people drawing, because it's more difficult to stich parts of videos of different drawings together, but I guess you need to film like 5 to get a good one.
For a 15 minutes talk, I had to film each "slide" like 4 or 5 times, and then glue them together. It was like 4 hours making the video and 4 hours editing, to get a (not professional) 15 minutes talk.
I'm not sure about videos of people drawing, because it's more difficult to stich parts of videos of different drawings together, but I guess you need to film like 5 to get a good one.
Good luck and keep trying!