A long time ago, I wrote and maintained a fairly used Userscript plugin to scrape and download YouTube videos. Let me tell you -- without constant updates (which I've gotten complacent of by using `pip install --upgrade` with youtube-dl), I have forgotten just how much of a hassle it is to constantly fix the HTML parser used to identify and generate download URLs. The reality is, any front-end source code change on YouTube would potentially break the script, sometimes necessitating complete re-write of the parsing scheme. That is all to say, I hope you've set aside ample time and coffee for this hobby...