I recently knifed a scene i required from a DVD movie using mpeg cutter and this was saved as an mpeg file. However though i am sure i knifed 60 seconds it plays back only around 40 seconds or so when i play it back on wmp11 my media player. It happended to all the 4 clips from different DVD movies

Any solutions and help on this problem? Yes i admit this is a copy of a DVD shrunk from DVD 9 size to DVD 5 size (i.e. compressed) but what is really the problem and its remedy?