Now you can, using AirPlay!
AirPlay is a new Apple thing. Using Home Sharing, another new Apple capability, AirPlay "pushes" video streams from an iOS-based handheld device such as iPad, iPhone, and iPod Touch over to an Apple TV 2 and thus onto the screen (and into the speakers) of an HDTV.
Given the advent of Home Sharing and AirPlay, it would be nice if there were an app for Apple mobile devices — the latest iPads, iPhones, iPod Touches — that would AirPlay videos streamed from a host computer over to an Apple TV 2 and its connected TV screen.
Air Video can do that.
Air Video, in contrast to Apple's own iPod app, has the advantage that the video files don't have to be synced the iOS handheld itself. They can reside on a Mac or PC connected to the same home WiFi network as the iOS device is connected to.
Air Video actually comes in two pieces, a client app that runs on an iOS 4.x-based mobile device from Apple, such as an iPad or iPhone or iPod Touch, and a server application that runs on a Mac or a Windows PC. (See the Air Video site to get the server software that matches your computer platform.)
If you're using an iPad, Air Video looks like this:
This is, of course, not Air Video's full-screen view of the movie, but the full-screen view likewise affords AirPlay capability. You can tell by the little icon that looks like this:
It's the AirPlay icon. Touch it, and an AirPlay selector menu appears, as shown in the earlier image. This menu shows all the AirPlay-capable devices in your home network. In the menu shown above, you can choose "iPad" or "Apple TV." The former puts the movie on the iPad's screen, while the latter shunts it onto the screen of the TV that is hooked to an Apple TV.
Notice that Home Sharing and AirPlay, used in tandem with Air Video, serve to integrate a Mac, an Apple handheld such as an iPad, and an Apple TV.
True, you can substitute a Windows platform for the Mac as the server machine that houses the videos to be streamed across the home network. Still, Apple hopes you won't, and that your will furthermore use one of its AirPort Extreme base stations as your network router ...
... and also that Apple's iTunes Store will be the source of the movie and TV show files that this little klatch of high-tech gadgetry is asked to stream. But that adds yet another wrinkle, since the movies and TV shows you download from the iTunes Store are DRM-protected. That means Air Video can't play them ...
... and yet Air Video does let you opt to watch such DRM-protected movies in the Safari web browser on the iPad/iPhone/iPod Touch. So when you play them in Air Video, they open in Safari ... which, like Air Video itself, has an AirPlay icon that can shunt playback to an Apple TV.
The AirPlay icon now appears in Air Video, in the iPad app, in the Videos app, and in Safari (among other apps) on an Apple handheld device like an iPad, iPhone, or iPod Touch. So all those apps can shunt video and/or just plain audio to Apple-branded co-conspirators such as an Apple TV ... or to an Apple AirPort Express wireless base station that can feed the digital audio streams it receives an analog signals to a home entertainment system.
The computer industry has long talked about integrating computers and home entertainment. With Home Sharing and AirPlay, Apple has taken great strides in that direction.