What strikes me is how the Apple TV is really in the "good enough" zone for iOS and recent Macbook users. After so many years there's no clearly better solutions to show some random content on the TV.
I simply want any device to send a signal to my TV. It's trivial with cables, modern wireless technology can cheaply carry high quality signals, and the only thing standing in the way is the copyright mafia.
There's absolutely nothing stopping you from loading a DRM-free h.264 file on another one of your Apple devices and streaming that over AirPlay. And HTML5 video in Mobile Safari works beautifully.
That's the problem. Apple has DRMd the protocol so you have to be using an Apple device to send things to it.
For video streaming, you basically just have to send it a URL to a video file, and it'll stream and play it for you just fine.
(1) my guest who recorded the video with his own phone.