Thanks for the review. From the D5000 Users Manual: "Maximum Size Each movie file can be up to 2 GB in size. The maximum length is 5 min for movies with a frame size of 1280 × 720, 20 min for other movies; note that depending on memory card write speed, shooting may end before this length is reached."
It seems the write speed of the memory card could also reduce the maximum time. Good Luck and Enjoy your nIKONS!