We didn't phrase our question correctly. We did try the preview for this particular video and it did not work (although previously it has - preview did not open), so we made a copy of the partially downloaded file (about 50%) and opened it in the VLC player (which usually works even for files which have the pieces downloaded separately) and it showed a black screen as it played with no sound. Of course, this should have given us a clue as to what was coming, but we decided to finish the download and see anyway, but it is still stuck at 98%. Usually the VLC player allows you to see enough of a preview that you can at least see what the file is and approximate quality.

I guess this is the best we can do....

However for an application etc you can't preview it, so don't know until you have downloaded it all. It seems that there should be more information attached to the files so one can tell. Is there anyway to do this, other than use a different software for downloading from a torrrent, which does have information attached to it?

I like Limewire and it behaves well, more than I can say for Azureus.