Open nautilus on a director, and then from a shell in the same directory create a 0-lenght file with a video extension, like .avi or .MTS. Nautilus immediately crash trying to render the preview.
(0)samsung-romano:~/tmp% touch 00000.MTS
(0)samsung-romano:~/tmp% totem-video-thumbnailer couldn't open file 'file:///home/romano/tmp/00000.MTS'
(nautilus:11002): GdkPixbuf-CRITICAL **: gdk_pixbuf_loader_close: assertion 'GDK_IS_PIXBUF_LOADER (loader)' failed
(nautilus:11002): GdkPixbuf-CRITICAL **: gdk_pixbuf_loader_get_pixbuf: assertion 'GDK_IS_PIXBUF_LOADER (loader)' failed
sys:1: Warning: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
[1] + 11002 segmentation fault (core dumped) nautilus .
This is clearly a crash in the thumbnailer; I remember a similar problem with malformed SVG files. I think that nautilus should be protected by crashing thumbnailers...
ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: nautilus 1:3.8.2-0ubuntu2
ProcVersionSignature: Ubuntu 3.8.0-31.46-generic 3.8.13.8
Uname: Linux 3.8.0-31-generic x86_64
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
Date: Sat Nov 2 19:11:30 2013
GsettingsChanges: b'org.gnome.nautilus.window-state' b'geometry' b"'1193x738+0+27'"
InstallationDate: Installed on 2013-09-30 (33 days ago)
InstallationMedia: Ubuntu-GNOME 13.04 "Raring Ringtail" - Release amd64 (20130424)
MarkForUpload: True
SourcePackage: nautilus
UpgradeStatus: Upgraded to saucy on 2013-10-18 (15 days ago)
Thank you for your bug report, could you try to uninstall python-nautilus and see if that's still an issue?