I've become a convert to Zotero[1], even though I'm not an academic. It will automatically snapshot websites (although paywalls and such can trip it up) and for many academic sites will find a PDF version and attach it. For anything it can't automatically archive, it's easy to attach or provide a link to your personal archive version. When I need to manually archive something, wget as:

    wget --mirror --convert-links --adjust-extension --page-requisites --no-parent https://site-to-download.com

For videos, youtube-dl or its successor, yt-dlp[2] work well.

1 https://www.zotero.org/

2 https://github.com/yt-dlp/yt-dlp