This is a bug. Thom knows about it, and told me it is a query issue as to whether the Orbiter(gen?) knows whether to display a drive for the MD. If the MD has a DVD drive itself then it isn't a problem. This occurs if the MD doesn't have a DVD drive. As a workaround, I manually add a Disk_Drive device to the MD in the web admin, then you have the functionality just fine after a regen and reload. You may end up with it getting confused and displaying even more drives, but you can just ignore that and play remote DVDs anyway. Otherwise, you can use the media map to start playing the DVD on the system with the drive, the 'bounce' that stream over to the MD that doesn't have one.