https://rg3.github.io/youtube-dl is the tool I use for this.
You can download a single video or an entire playlist.
You can also use Firefox + http://www.downloadhelper.net extension.
The Downloadhelper extension also allows scraping HTS streams, by playing them + recording the stream + dumping the stream into a file.
Upvote on https://www.pexels.com/videos/
If you need some help with techniques, here are five simple techniques you can add to your post production workflow: https://vidico.com/news/5-effective-video-editing-techniques-every-marketer-should-know/