Major Nelson's latest blogcast confirms (around min. 44:00) that the HD-DVD add-on won't support HDMI or DVI digital video output. That would mean that if and when the film studios decide to support the Image Constraint Token (ICT), the Xbox 360 will be forced to down-res the display output.
The addon will use the video output of the console and while Microsoft still doesn't want to officially deny the possibility of a HDMI cable/pack for the Xbox 360 it doesn't look very likely
The addon will use the video output of the console and while Microsoft still doesn't want to officially deny the possibility of a HDMI cable/pack for the Xbox 360 it doesn't look very likely