How do you delete videos from a gopro camera?

In the settings on the Hero 2 and Hero 3, there will be a trash can at the end of the settings menu. You can either delete the last file on the SD card (either a photo or video depending on what you last took) or you can delete everything that is on your SD card which reformats it as well. Your best bet is putting the SD card into your computer and deleting what you want from there rather than taking a chance with the GoPro.