If you are pushing traffic to youtube videos, the analytics there should tell you ingress sites, including the NGDF.
I think this forum is pretty advanced in terms of years, and the effort of prying open this old PHP instance might introduce more problems than answers. This site has a wealth of information, and is quietly running along just fine. In addition to adding php code, any counter would involve adding another table, or altering a table, and that might make the site pretty cranky.
As someone who writes web servers for a day job, I would discourage changes unless someone is hellbent on spending a great deal of time debugging it.
-Nick