I am unsure whether or not this is a Firefox issue or a VideoLAN issue, if you press the back button in Firefox once a video file loads after being completely downloaded and begins to play in Firefox, Firefox no longer responds.
I am using Firefox 1.5.0.3 and VideoLAN 0.8.5 on WinXP SP2 all updates with the following hardware,
Laptop
Mobile Intel Celeron CPU 1333MHz
integrated Intel 82830M Graphics Controller
ESS Allegro PCI Audio