Put the quality on 1080p and see how some of the profiles are just unnamed and you can add them as friends and its somehow going to send a friend request to nobody.

Ive seen that before, I think those are deleted user IDs that you are entering there.

That number is the entry number of each user, that way you can see who are the oldest users on this site which is pretty cool. I noticed that between the regular users Gennady is the oldest, also my first user on FR is one of the oldest, surely older than all the regular users in here :)

As a mod Ive used this technique to investigate multiaccounting and it is very useful.