Walmart mp3 player question?

a couple days ago i was on walmart.com looking at video picture and music mp3 players and evey time i looked at a two gb mp3 player it would say it can play up to 7 hours of video blah blah blah but i tested it my self and just abut evey half hour 1gb would go by so can any one tell me how this is possable or is walmart.com just being stuped