In the video, it looks like you're dealing with a poorly prepped repair from years past. If you have material flaking off, you need to get all of that off or your nex paint will do the same thing.
The picture looks like either lots of sanding with 36 grit or lots of beaching and sand bar hits. You'll keep burning through if you try to sand that smooth.
Post some farther out pictures of each side. If the whole hull is like this, and you want it back to factory, you'll end up gel coating the entire bottom. That's a huge job.
