Does somebody know how to do the same with PlexConnect user interface? I would like the ATV2 to start directly to Plex as I do not use the other applications (but still, I would like to be able to exit, in order to access settings).
You can do this if you have an ATV2 jailbroken by installing PlexConnect directly on the ATV itself. Look in the support folder for the ATV2 scripts to install it (more details are available ion the launchctl thread on it).