Flippa's drawing attention to a recent video posted on the weekend by a siteflipper exposing how some sellers of sites can continue to get a share of the buyer's Adsense income long after the site has been sold.
Actually, this scam has been around for a while and was covered first, I believe, in 2010 here followed later that year by a WF thread. This is how it works:
The seller installs a plugin (All in one Adsense and YPN) that handles Adsense revenue sharing prior to sale. This is, in itself, not suspicious. Many blogs allow guest posters and others to share the Adsense earning and that acts as an incentive for people to write content. Hubpages, DigitalPoint and others do it as well. So he could have been using a rev share model on his site prior to selling. However, what happens with the scam is that on transfering the site to you the seller sets his share of the Adsense revenue to zero. Unknown to you there are other parts of the php code that override this setting and continue to siphon off a share of your earnings. You continue to run the site completely oblivious to the fact that a percentage of all your future earnings is going to the seller.
I suppose this is a nice way for sellers to build what all those guru-followers like to drool about - passive income.
There are a lot of sharks around who have found far too many ways of scamming newbies (and a lot of vested interests driving newbies to jump into site buying). It's a sad state of affairs and not at all how the market used to be when I started buying sites