FF: 3.6.15 (20110303), SL Plug-in: 4.0.60129.0
I'm having no problems with it at all, even on previous versions of FF and SL, only the 1st time I run in fullscreen I have to add an exception (by popup warning) to let FF launch SL in fullscreen for Ch9 site (url)
Some camera drivers are bugged and crash cause any access to the cam (even if only to inspect the cam name and supported resolutions) trigger the cam app to launch.
I see lots of this behavior cause on my old work I have to deal with video conferencing (by apps and browser apps) and every cam (and even on every model inside the same brand) have corner cases
Try see if the cam have updated drivers, but not much to do unless write a report for SL forum and cam tech forum (if have)