Video platforms should be required by law to let people download videos as a non-proprietary file (usually MP4 or webm) in the download folder.
Third-party tools like youtube-dl and ytdlp exist, but they often stop working because video platforms like YouTube make changes to their site or deliberately try to counteract them.
If downloading videos is too difficult, many people simply don't bother, which causes videos that would otherwise have been preserved to become lost media.
so they can sell YouTube Premium's "downloading" feature.
However, the YouTube premium "downloading" feature does not result in an MP4 or WEBM file, but in proprietary binary data that is stored with data lock-in, and are forcibly deleted after 30 days, making it useless for long-term preservation.