If I understand this right.. its just that the user you see bumping the bid has just his autobid set higher than the person who put in a bid on the item

http://offer.ebay.co.uk/ws/eBayISAPI...tem=7172783209

If you look at the bidding history on this item you will see that user "nig_rob" had a high autobid that I had to find so he has allot of bids from 20 to 41, which was his maximum price. I then put my autobidder on 45, and since his highest bid was 41 I won the auction with £42
Hope this was easy to understand