From observation, as the originator of Samples,
they are resident for a period, then can be downloaded.
However, after time can no longer be downloaded.
If it would be so for visitors, may as well auto-remove.

If files and pictures are uploaded using the attachment function, there isn't an expire date; in fact f.e. you can download examples from 10 years ago (like here).

Andrey told me that they are rewriting the backend of the website to a more recent .NET, ready to run on linux, so things might not work as expected for some time.

Thanks Davide.
It doctored itself, I can download my very first Bessel sample.