But the biggest danger is that videos and channels can get removed by any, all, or no reason.
-Copyright middlemen/parasites
-Trolls
-Shifts in what’s politically or advertiser acceptable (see: https://www.reddit.com/r/youtube/comments/14ddlng/unalived/)
-Massive data loss (see myspace)
-And especially the capricious whims of the channel owner.
A few years ago I realized an old playlist of mine was basically swiss cheese due to how many videos had been removed.
If you value it, save it now, because it will be gone sooner than you are prepared for.
There are many ways to handle automated saving of channels, including some gui frontends, but offhand the one I use and modify is: https://github.com/TheFrenchGhosty/TheFrenchGhostys-Ultimate...