As far as I understand, when you create a user, he is a member by default Domain Users. You cannot see it in the attribute memberOf, but you can see it in primaryGroupID (513=(GROUP_RID_USERS)). You cannot suppress it unless you add a group and make it primaryGoup for a given user.

A command like the one below allows you to create a list of people related to Domain Users.
ldifde -f file.ldf -d "ou=Monou,dc=dom,dc=fr" -r "(&(objectclass=user)(|(primaryGroupID=513)(memberOf=CN=Utilisateurs du domaine,CN=Users,DC=dom,DC=fr)))"
be careful
- French names are used here ("Utilisateurs du domaine" = "Domain Users")
- Windows 2008 R2 ldifde
Administrator, memberOf.
.
. . . .
MonGroupe.

RID, .
