Its not just people with broadband connects. There have been sniper services/apps out there for quite a while that let you pick the maximum price you are willing to pay, and within the last few seconds of the auction, make a bid that is just above the highest. My guess is that Ebay implemented their proxy (or whatever they are calling it) service because of these snipers chewing up bandwidth to keep track of the times/bids - automation can refresh a lot quicker than a person can