I guess it is just cryptsy pool VTC reserves own by customers.
OK, new idea, but why should users VTC deposits only have one way each day by day

Because people hold!
There is a small account, that sends 500 VTC to the big account, when it reaches a certain level.
If someone withdraws, the withdrawal is sent from the small acount.
So this is just all the VTCs people send to cryptsy (or whatever plattform)
This theory sounds better to me than the Mysterious-Man buying all vertcoins.