this is not an official announcement, but is from what i observed and know:
The credits are mainly gained according to the number of posts/ the size of posts you make.
-It started taking place only recently, so when you see new members having as much credits as old members it means that in the last period of time, they have posted approximately the same, because the credits did not take into account previous posts.
-the credits are NOT used for VIP membership, it is quite obvious than the VIP membership will be a hand picked selection, not a program made one
-i guess that Dave wants to implement the credits system in order to manage access to the downloads area, but i am not sure
-THE MOST IMPORTANT part:
"Just ignore them and behave as you would normally do-like a normal member.
If the credits are going to be used for something important, i guess there will be an official announcement by the moderator team explaining us everything. Maybe they are just testing new systems."