There is also now an officially recommended way to manage which thumbnails are generated in Thunar by tumbler, the Xfce thumbnailing service. Using the method described below means nothing will need to be uninstalled from the gstreamer set of packages, and all other thumbnails (apart from video) will be generated.
However, it is important to note that this is only possible if you have tumbler 0.1.27, although this will be at least the version in Raring (13.04). If you are on Xubuntu 12.10, you only need to enable the Xfce 4.12 ppa to get the latest version of tumbler.
On the Xfce announce mailing lists for January 2013, it was noted that, regarding tumbler 0.1.27,
This release ships a config file installed in the xdg directory to
control the various plugins (especially the priority). There is also a
cover download plugin (dependency is libcurl), but this has been
disabled by default.
How to enable and disable various plugins is explained on the Xfce official page, but briefly here's how it works. As noted in the explanation, if you want to customise the tumbler rc file, you can make a tumbler folder in your user-specific configuration folder and then copy tumbler.rc from /etc/xdg/tumbler to that folder:
cd ${XDG_CONFIG_HOME:-$HOME/.config}
mkdir -p tumbler
cd tumbler
cp /etc/xdg/tumbler/tumbler.rc .
Now, edit the file with your preferred text editor, e.g.
gedit tumbler.rc
and you will see something like this sample rc file, which has sections for video, image and other thumbnailer plugins.
As an example, you could find the section Video Thumbnailers in the file above and set Disabled=true in the sections for the ffmpegthumbnailer and the gstreamer plugins. Using this method you do not have to remove gstreamer0.10-plugins to stop video thumbnails being shown.
Excerpt from the Video Thumbnailers section of tumbler.rc:
# ffmpegthumbnailer plugin
[FfmegThumbnailer]
Disabled=true
Priority=2
Locations=
MaxFileSize=0
# GStreamer plugin
[GstThumbnailer]
Disabled=true
Priority=1
Locations=
MaxFileSize=0
If at some later point you find that you do not want to entirely disable the video plugins, you could instead use Disabled=false to re-enable them and set a value for the MaxFileSize, so that only files up to a certain size were shown. This would solve problems with high memory usage when thumbnails for very large files are being generated.
Note: after making any changes to tumbler.rc , it is crucial that you log out and log in again. Video thumbnailing for those two plugins, for example, would not be disabled until you logged in again.
Remember, this will only work if you have tumbler 0.1.27 or a later version installed.
Every post out there that tries to fix the problem of thumbnails they do the following or something similar
$ killall thunar
$ sudo apt install tumbler tumbler-plugins-extra ffmpegthumbnailer
$ thunar -q
and that's it, they open thunar, and thumbnails magically appears, but the ugly truth is You need to restart your machine.
Best Answer
Just make the cache available to programs, by running:
This also works for more programs like Image Viewer that uses the same cache file.