It will link to the first author profile matching the member. That's either an author profile with their username and no member ID, or an author profile of any name matching their member ID.

Okay, just ran into this again. What I did was:-

1) Add a download and assigned it to an author who isn't a member (a band name).
2) Visited that author profile and edited it to reflect the band.
3) Saved it, to find those changes on my profile (admin). (I am still the owner of that download, the author is the band).

As a related issue (to that particular download) when I click the links from the homepage (random download) I get the following error:-

A query that had to return something returned nothing: SELECT category_id FROM cms10_download_downloads WHERE (id=656) (version: 10 RC8, PHP version: 5.6.20, URL: /site/index.php?page=downloads&type=entry&id=656)

Random download block URL points to: http://localhost/site/index.php?page=downloads&type=entry&id=656

Download of the week block URL points to: http://localhost/site/index.php?page=downloads&type=entry&id=audio%2Fmarmozets-the-weird

No idea where the 656 came from? Would be a strange id for the first added download.

(Click to enlarge)

Uploaded screenshot to depict that the random download block isn't showing the download thumbnail.

New problem fixed, relates to content-translation support.

Ah, you were right, it was a bug