The estimated disk space required by the "burn disk" tool is always hopelessly wrong. I'm always told there is not enough room when in reality there is plenty. This make burning a disk often and trial and error method. I find on a regular 4.7GB DVD disk I can get 25 minuets of 25Mbps Blu-ray video where as the "not enough disk space" warning comes on at around 18 minuets.