Upload & Sell: Off
What on earth ? Of course he's not. That terminology is for stolen property. This guy seems to be buying items legitimately and then re-selling them, perfectly legal (thought the IRS might want a word) . Tons of people just want to get rid as quickly as possible and not bother trying to obtain the high price, or they acquire the items from family/friends and really don't know the real value.
Yep, he is definitely not doing anything illegal. He pays what people ask for their goods, and sells for what others are willing to give him.
You could, I suppose, argue that he's in a moral grey area where it's not exactly the most honest thing to avoid telling private sellers that they are undervaluing their goods, but it's not illegal.
He pays taxes, as well. Last I knew, he had a pretty expensive accountant taking care of his finances and making sure he was on the up-and-up with the IRS.