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.