For the average user, file sharing is already solved. If it’s a small file, you just send it via an IM app. If it’s a large file, you upload it to cloud storage and share a link
Uploading Gigabytes of media via p2p takes minutes nowadays, but you have to either pay or use p2p software to actually send it to another person.
Skype file transfer used to be p2p and it was a huge pain. If one side closed their laptop or something it would just kill the transfer.
2. Your assessment of P2P being "unworkable" is just mistaken (besides the obvious fact that two machines have to be online at the same time). Syncthing works great, wormhole worked fine, filepizza worked fine. I remember long time ago I simply used a magnet with a bunch of open trackers attached and it worked wonderful.
I'd wager a miniscule amount of people know how to do this.
But if they don’t have the video on their phone, they film it with their phone and then share it on WhatsApp.
That’s what the average user does.