As it is now, the remaining time in the AH is more than user unfriendly.
First of, the time spans far to many hours in "Very long" and "long", 48 to 24, and 24 to about 4 hours. 20 hours is a hell of a difference.
Second, who's idea was it for a bid to increase the time of the auction? "Very short" should be 5 minutes, but if more than one person thinks "Ha, Imma be clever and bid only in the last 5 minutes to keep the price low" a bloody bid-war ensues which is exacly what last second bidding wants to prevent. 5 minutes can easily become over 15 Minutes, hitting 30 minutes if both partys really want it. It is favorable for the one who put the auction up, sure, but this is a bad joke. To make a hard profit you have the BO option, there is no need to screw with the bidding option like this.
My suggestion would be to change the time displayed to something more helpful like ">24h", "24-12h", "12-6h"... such things. Also, get rid of the "each auction increases remaining time"-thing. It's horrible.
Why not just have a timer for the auctions, like the mineral deposits and gates in the arcade? Have the time refresh each time you refresh the page. as far as the auctions getting more time for each bid at the end...thats good as it is, as you said before you can always click the buyout function.