What kind of camera is it? The amount of space consumed by movies depends on the camera and on which mode you choose. You can check the specs on the manufacturer's web site. For example, my Canon A640 is here: http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&fcategoryid=183&modelid=14109
For my camera, under the "specifications" tab there's a table that shows the camera uses up about 1,920KB per second. 1,920KB is about 2MB which is about 0.002GB. Therefore, a 1GB card could hold 1GB / 0.002GB = 500 seconds of video. 500 seconds / 60 = about 8 minutes plus a bit.
For your camera 1GB could hold more or less than that depending on what format it uses.