Go to page 53 in the User's Manual.
The longest continuous movie you can make is 25 minutes.
You can make many movies on a memory card, but none longer than 25 minutes.
A common type of limitation on many digital cameras.
Why does it always display 25 minutes for video, even with a 4GB SDHC card inserted? Even with low quality settings set? Even with TV quality (640x480) set? How much video can actually fit on a 4GB card on TV quality?