it isn't a real download, because you don't have access to the raw file.
It’s a nice no-fuss solution if you just want to watch some videos offline (as mentioned, it’s not suitable for archival) and the device is iOS/Android.
The reason why your solution is bad is because your solution only solves the problem for certain imagined values of 'problem'.
We don't know what the playback user story is for OP -- is it a raspberry pi? is it a librem 5? -- and there's no way to know that the user's problem is in fact solved, as you claim.
Your solution makes assumptions, and there's no way to know if they're reasonable, because this is HN, not Best Buy, and some of us are on some pretty interesting (and DRM-free) hardware. That's why it's bad.