In a blog radio interview with a Motorola developer, when asked about how the Droid X’s HDMI-out could be used, the following answer was given by the Moto dev:
"The only time that we are enabling the HDMI driver on the device is when you are in the gallery mode. [...] The HDMI driver is not active any time outside the gallery"
As Android users are aware, gallery is the native photo and recorded video viewing application on Android devices. The mechanism of controlling the HDMI-out on the Droid X remains unknown, but for the time being it appears that, without root, the Droid X’s HDMI out is extremely limited in its usefulness.