Samsung TV wont play video files from external HD

Hi all,

I'm trying to fix a problem a mate is having with his TV. He has a hard drive with video files on it that were taken from various occasions on 3 different cameras. Some are mp4's and a few other types.

When I plug the hard drive in via usb 2 and go to the usb option on the source menu, it shows an option for photos, and music but not for video. It does show the 4 folders and the names he has on them but they appear empty. The info at the top of the screen shows that theres 100GB used on the drive and 150GB remaining.. so the TV can see theres something on the drive.. its just not showing them.

Samsung USA support

The above is a US version of support for using an iPod an an external and although its not what Im after, it shows the music, pictures, movie thing Im on about.. except we cant see a movie option.

Any help really appreciated!