From Debian changelog Note the date.
"xbindkeys (1.8.6-1) unstable; urgency=medium
* New upstream version
- Bug fix: Do not grab keysym not mapped on keyboard.
Prevent a AnyKey grab, this should (Closes: #447026)
* Bug fix: "New release blocks seahorse" (Closes: #628654).
We now put the autostart script elsewhere and place a file in
/etc/xdg/autostart. In the common Desktop Environments this should
have xbindkeys still start automatically, but without the problems the
old way of using /etc/X11/Xsession.d gave us.
Users whose environment does not make use of /etc/xdg/autostart do
need to manually start xbindkeys, either by just running it from their
xsession or by executing /usr/bin/xbindkeys_autostart
* Bug fix: "Please update homepage in man page", thanks to Mathieu
Malaterre (Closes: #640477).
* Bug fix: "[xbindkeys] xbindkeys defaults file should only be
examples", thanks to Dean Evans (Closes: #657965).
* Update guile version
-- Joerg Jaspert <firstname.lastname@example.org
> Sun, 16 Feb 2014 13:59:57 +0100"
I would suspect https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=799627
as the cause of the seg fault.
A lot of this gtk3 "stuff" going around the last few weeks.
I do not have any advice over the media keys, I don't use.