If you are just trying to set what VLC plays (rather than reduce the size of the file), you could try my Clipper extension at
http://addons.videolan.org/content/show ... ent=163792. It does not trim the video file itself, nor make other changes to the file. There is no reencoding so no loss of resolution, etc. Clipper allows you to go through a video (or several videos) and decide where to start and stop each one. After you save the playlist with that information, you (and anyone else) can load the playlist with VLC''s "Media | Open File" menu item, without using the extension.