I believe you have to pay the 5 hour minimum and then $100.00 for each hour after that.
Our ceremony was in Epcot - our motorcoach started picking everyone up at I believe 7:30am or 8:00am. First it picked up everyone staying at the POFQ, then everyone from The Boardwalk, (rthese were the only 2 resorts we used) it then brought everyone to Epcot for the ceremony. After the ceremony, it brought everyone to ADH for our reception. Our reception lasted until 3:00. We had the motorcoach wait around through our reception to take everyone back to their resort after our reception. I believe it also made a trip at 1:30 and 2:30 if anyone was interested in going back to their resort early. The final motorcoach was at 3:30.
So, we had the motorcoach from 7:30am to 3:30pm - this was the minimum 5 hours plus another 3 hours that we paid for. You can have the motorcoach not take your guests back to their resort after the reception and use it for less hours. We figured we did not want people to have to get back on their own.
We did have a DP in Epcot later that night that we had everyone take Disney transportation to so we did not pay for a private bus later that same night.
Any other disbrides in the know please confirm if this is correct.
Linda