those are guest accounts, they're treated mostly like normal accounts, except you can't see their profile pages. if a name is entered into the player field, and it doesn't match up with an already created account, a guest account is made.

not everyone wants to create a SRC account. :P personally, I'd like to see a "is guest" option for names that might've already been taken, but aren't that person. I usually put ' around the name to enforce it being added as guest.

If submissions to this site were gonna be limited to registered account names (Which can be changed) then you wouldn't see very many runs for popular games with established communities on external sites.