What is a Bid extension

Where there is bidding activity on a particular lot within 5 minutes (300 seconds) prior to the lot’s published closing time, there will be a 5 minute (300 seconds) bidding extension on that lot starting from the set closing time, and extended until only one bidder remains.

These extensions will continue indefinitely until there is no more bidding activity on the lot for a period of 5 minutes (300 seconds) implying that there is no further interest.