So that's exactly the same as putting a high bid in with EBay but you pay 78p extra
Not necessarily the same, if it were the same, the auction sniping thing wouldn't be as huge as it is.
If you bid more than anyone else, you're always going to get it, but why let other people put the price up bidding in small amounts against you.
If you put a high bid on an item on day one (say £100) and I keep bidding against you during the week in small amounts up to £75, you'd win, but you'll pay £76.
Now, if I bid on the same item, and was the highest bidder at £14 (with a few days to go) I'd leave it there thinking I was probably going to win. I might have my maximum bid at £28 but was still hoping to get the item for £14.
If you then bid your £100 at the last minute you get the same thing for £29. You've outbid me, but I don't have time to react pushing the price you'll pay up.
This is the way most eBay auctions play out, it all happens in the last 5 secs. People think being the highest bidder is important, they keep bidding small amount until they're just a pound or two over the highest bid. If you can't be at your computer to snipe it yourself, then Auction Sniper is a nice way to save yourself some cash.