remember to delete ~/.cache/gstreamer-1.0 every time you add an extension to force gstreamer to re-scan its plugins
yes this was a good tip. without it i could not see the error msg after i typed
tc@box:~$ XDG_RUNTIME_DIR=/home/tc cheese -d /dev/video0
summary: cheese started, but it did not detect (neither inside its functional menu) my webcam (/dev/video0).
tested in Virtualbox (in win10) in the same time cheese, vlc, and guvcviewer. both vlc and guvcviewer works (led light on webcam etc), but not cheese.
the error is about
libva (device), called by both vlc and guvcviewer. so it is not libva, but maybe gstream calling it with wrong parameters...
i tried (without succes) to mess with load/unload libavdevice{-,3,4}.tcz but maybe this lib is about sound not video. I have lost track of how many tcz i loaded, almost all (resonable) gkt* and gst* and gnome*. and played with 'XDG-*=name cheese' etc.
EDIT: and yes, dbus was started with something like /usr/locale/etc/init.d/dbus (start then status).