This can be had for free with uBlock Origin ( I never see an ad on YT ).

Yes, and I'm sure you can jailbreak/root your mobile devices or use a VPN running Pi-hole to remove all YouTube ads. You can also download YouTube videos with youtube-dl (another feature of YouTube Premium). But for me it's well worth the $12 a month to remove ads and get mobile downloads without any hassle or nonsense.

That works only on desktop.

YouTube Vanced works on Android.

Also, Firefox + Unblock.

or anything with that has firefox.