Not sure how to go about opening and veiwing .mpeg fines. Running OS X 10.3.9
If you dint change the default settings of your computer just double click on the mpeg1 file icon and it should automatically launch Quicktime. If it does not click on the file icon>got to File>Get info> Open with> select Quicktime Player. Click on change all if you want it to become your mpeg default application.