It depends on your needs, but sure, there's tools out there. I think that's what the *arr stack is all about but people have been doing it manually for as long as the internet's been around.

Whatever media you're downloading, you only have to hold onto what you want though. So like, yeah, video eats up storage space. When you're curating a collection you have to decide what's worth keeping, what might be worth backing up to physical media, and when it's worth expanding your storage.

A torrent uses Peer-to-peer (P2P) networking. The way it works is that each client downloading a file is potentially also uploading a file. If you have a lot of peers, it typically moves faster. A popular torrent could let you download media far quicker than you could you consume it.

This also means it can run afoul copyright law depending on your jurisdiction. Example: in Canada it's only a violation to upload copyrighted content, but downloading isn't actually a crime. That said, not all torrented files are protected by copyright, it's a technology that can be used for any file.

If you don't want people to see what you're downloading or are wondering if you might receive a copyright strike, I strongly encourage you to read the FAQ and ISP Complaints sections, and pay particular attention to what they have to say about VPNs.