What's a good way to keep my videos on physical media?

Don't rely on a single disc or drive. Keep three copies, use more than one type of storage, and put at least one copy in a different location. That way a failed drive or a fire in one place doesn't take everything with it.

Check the copies on a regular schedule. Open some videos and make sure both picture and sound play, and verify the files for corruption where you can. Eventually you'll need to copy them to newer media rather than expecting any device to last forever.

For a straightforward start, copy the videos to external hard drives. They give you plenty of space without having to split everything across lots of discs. Store one somewhere cool and dry, and keep another copy elsewhere.

A drive sitting in a drawer isn't maintenance-free, though. Plug it in periodically, check the files, and replace it if it starts having problems.

DVDs can work, but a large video collection may take a lot of discs and time to write. Blu-ray is another optical option. Keep in mind that you'll also need a compatible drive to read whichever discs you choose later.

I'd use discs as an additional copy rather than the only one, and test that you can read them after writing.

There's no physical format that guarantees you'll never lose a video. The files also need to remain playable as software and formats change, so plan to move the collection to newer storage and convert formats when necessary.

Online backup can be another layer alongside physical copies. It doesn't replace checking that the backup is actually current and readable.