Google seems to have implemented a 'phantom feature' into the new Android Market that they released on Dec 10: Video Previews for Apps. This feature is currently not yet integrated into the Android Market, but an Appsfire blog shares that Google has included the capability into the API of the new Market, and that they have tapped into it and incorporated it into their third party portal. For those unfamiliar with Appsfire, their product makes it much easier to find apps that you are looking for on the Market.
It's interesting that Google didn't mention this in their features list when they released the new Market, but perhaps they still have some 'kinks' to work out before they implement it fully. This video demo idea is a great one. I can't count how many times i've seen an interesting looking app, but passed it up because I didn't really know what it does. A video demo should greatly enhance app sales on the Android Market.