If you really want to be safe AND upload it in MEGA, consider only making the links accessible to you and you alone i.e. your personal use.

If you are confident that they're lost media, maybe they can go to archive.org.

You can upload content to Archive.org yourself rather than mega and get an extra layer of defense against legal trouble, as you wouldn't be directly responsible for hosting the content. They would take the uploaded item down if they got a DMCA, but mega is more likely to take down the whole folder.

Would also keep the content more accessible long term. Tons of dead mega links all over the internet.

You're distributing copyrighted material so the short answer is "Yes", but the longer answer is "Probably, but it really depends on a lot of factors that you haven't disclosed, like your location. It could certainly get you in trouble with MEGA regardless; whether it will get you in trouble with the law comes in large part down to the laws governing wherever you live."

The chances of anything coming of it are another matter entirely and you may consider it worth the risk if you feel that chance is low enough.

Yes