I had a problem and found a fix, so I thought I'd post it here.
I have two Macs, a MacBook and a Mac Mini*. I had downloaded a .flv off the web (using Downloadhelper with Firefox) onto an external drive attached via FireWire to the Mini. From my MacBook, after connecting to the Mini over my LAN, VLC played the file fine. From the Mini, however, VLC crashed when I selected the file in the Open dialog. VLC would repeatedly crash even BEFORE I clicked on the Open button.
I tried trashing Preferences and clicked "Report" to send several reports to Apple. I hope this message somehow finds its way to whomever reads them.
Perian had been installed and later removed from the Mini. Reinstalling Perian fixed the problem.
--Gil
* - both running MacOS 10.6.8 & VLC 1.1.12