trim video without transcoding on lion

Not sure whether Snow Leopard Quick Time will work if you restore it on Lion, since I don't have that version to restore.

However, there are a few freeware utilities that can clip videos:

• According to this Super User thread, VLC can both cut clips of video without transcoding and also transcode entire streams/files into different formats (see the VLC wiki).
• How-to Geek has a guide that shows how to quickly cut clips from videos with Avidemux.
• SimpleMovieX has a free (unlimited) trial that can also do the trick. The main downside is that the trial version is slower than the paid version.
• MPEG Streamclip is another freeware tool that provides similar functionality.

One of these utilities may provide the functionality that you're looking for.