I remember using youtube-dl back 8 years or so ago when I was an undergrad in India to download MIT OCW lectures (and others e.g. SICP vidoes, Coursera), becaus

I remember using youtube-dl back 8 years or so ago when I was an undergrad in India to download MIT OCW lectures (and others e.g. SICP vidoes, Coursera), because bandwidth was limited, download was capped, and 3G was too expensive. I could watch these videos anywhere, and whenever I wanted. And I'm pretty sure non of those videos had (or even have) ads.