Comment # 5 on bug 959911 from Panagiotis Georgiadis

Yeah, my Firefox doesn't crash anymore:D  I found that the problem might be
related to the MSE (Media Source Extensions) since some options are toggled in
the new FF version. Notable, please check the about:config for more
information:

before the update
~~~~~~~~~~~~~~~~~~
media.mediasource.enabled;false
media.mediasource.webm.enabled;false
media.fragmented-mp4.ffmpeg.enabled;false

after the update:
~~~~~~~~~~~~~~~~~~
media.mediasource.enabled;true
media.mediasource.webm.enabled;true
media.fragmented-mp4.ffmpeg.enabled;true

I also was using 'packman' repository. As soon as I remove all the packages
from packman (either deleted or change vendor) the new Firefox 43.0-6.1 doesn't
crash anymore.

So, I guess if you want to reproduce it, feel free to add packman repo:

zypper ar -f -n packman
http://ftp.gwdg.de/pub/linux/misc/packman/suse/openSUSE_Leap_42.1/ packman

and install, or update (change vendor) of the following packages:
http://pastebin.nue.suse.com/18758/src