Apparently, there's an unlisted feature of Anydvd HD. It also "allows one to display the output of your HD capable video card on multiple monitors.

With an ATI X1600 I have successfully displayed HD movies on both my desktop and HDTV simaltaniusly through DVI-D (desktop) and VGA (TV) using PowerDVD Ultra. Before AnyDVD/HD this could not be done and the docs for PowerDVD Ultra state that the second monitor need's to be disabled to watch a HD-DVD (I confirmed this prior to installing AnyDVD/HD).

Three cheers to James and company for this unlisted feature"--wdgoldstein

source: http://forum.slysoft.com/showthread.php?t=1640