I use 4K Video Downloader for downloading video clips of subjects I’m studying.  It’s excellent for many websites like YouTube, but many websites just won’t respond, and I can’t find any straightforward way to do this.

I’m on a very tight budget, so any free and easy-to-use programs that will let me do that would be great.  Many programs claim they will "work with hundreds of websites", but often don’t.

Any help appreciated.