I am also curious about this.

One of the flaws that traditional torrents suffer from is if all the downloaders want 1 file out of 10 and thus seed 1/10, the torrent can ever again be fully downloaded if the last seeder with 100% drops off.

I suspect this is not an issue for the demo since the DB seeding is probably being monitored, but as a technique? I could definitely see chunks of a DB not being available due to no one seeding 100%

Not in this case. Visitors to this site are only pulling data from a torrent, not hosting any data for other visitors. If you want to help host the torrent then you'd be seeding the whole database by default. Torrents are split into blocks and there is no easy way to choose to only download/seed specific blocks of a single file.

Pretty sure. Ideally there are a few always-on seeders for every db.