what is dbus daemon and why vlc needs it

I am working on a minimal rootfs based on buildroot. This error is solved for me after I have included the package "twm" in my rootfs. Then after the board is up I run following commands on the terminal:

export DISPLAY=:0
startx &

then run vlc


This way I got rid of this error.

Since you say that you have cross compiled vlc and facing dbus launch issues, I expect you are working on a minimal root fs.

Try doing this in your terminal before you run vlc:

$ export DISPLAY=:0

If you have compiled dbus with x11 support, then dbus-launch will succeed.