as far as #4 goes, look into software called "youtube-dl"  its incredible.
https://github.com/ytdl-org/youtube-dl it handles about 400 or so different websites.
as far as #2 - livestream integration in jitsi is actually a youtube okay so its a google feature, you're right. you can't even access it with developer api as the keys are differently hashed than any dev key, the ones they give to people with 1,000+ subscriptions have a different signing key/md5.
what else is there for streaming platforms? isnt there part of the jitsi suite that does this?
as far as uploading a recording: i think most people would benefit security wise much better with a panel to insert SFTP credentials or webdav credentials, all the "big guns" have TERRIBLE data sharing best practices with their un-named "3rd party partners." its one big orgiastic clusterf**** of data collection and it all ends up in the same places.
there is only one cloud service i trust, and that's tresorit, their data is stored in switzerland, and as you know they have different data exporting laws than any other country.
as far as cloud goes though, "if you're putting it on a hardddrive that isnt in your posession, and that harddrive comes with terms of use, and you have to pay for it," odds are your data is being shared, to some extent. i'd much rather have a 6-10tb local SSD raid array and just pay my ISP extra and put the entire thing behind a box with DNSMASQ and IPCHAINS firewalling..
I'm not paranoid, but I definitely have to say there is little security with how most implementations of the popular stuff goes.