Good questions. You'll find your answers by starting here:
https://groups.google.com/g/video-downloadhelper-q-and-a/c/BzPLK2YyL-s
That is a link you'll probably want to bookmark for easy reference. I recommend you read
that entire thread, if not now, eventually. As you read through that thread, you'll come
across a reference to the VDH license. You can skip quickly to that reference by doing a
string search on "philosophy" in there. That will reposition the page to the relevant
reference. There is a link in that reference that you should click. You'll find answers
to your questions & probably answers to a few questions you didn't think about asking.
Good luck!