Ghoelian

There’s the pretendo network, which continues support for the 3ds. Haven’t used it myself, but I think the miiverse network is also supported by them.

So at least you can still use miiverse to some extent, though probably with way fewer people.

Why would you downvote a video you haven’t even watched

Qbittorrent has a feature to execute a command on torrent complete iirc. You might be able to write a few ffmpeg commands to verify and delete/move/whatever based on that result. Not very user-friendly though ofc and requires some bash knowledge.