For what the Chromecast costs, even in a distributed video installation I like to put in 1 per TV/AVR. This way no matter what is going on with the matrix or distribution network, clients can always have a way to play something directly if needed or desired. Chromecasts do use CEC and as always that might cause problems with a control system, (if not set correctly - usually disabled/off) but in a simple system when used properly it actually supports power, input, play, pause stop and seek fwd, seek back through CEC.

The computer screen casting feature is still beta and for good reason, they haven't quite nailed it yet and it shows. The screen can be laggy and up to a 4 sec delay, which is impossible for games or video but OK for presentations and material that isn't so time-sensitive. I never present it as a feature to clients, but if they ask about it I always make them aware of its buggy nature and set their expectations low. It will no doubt improve in time, but its just not quite there yet.

Unlike Airplay, (except in screen casting mode) the stream doesn't need to get routed first to your phone/mobile and then to the Chromecast. Instead, the casting app 'tells' the Chromecast where to go, and it makes its own connection to YouTube, Netflix, or whatever directly so if your device that initiates the cast dies, locks or exits the app, the Chromecast will continue chugging along streaming away. (If its DRM content like Netflix or Play Music, I find that it will typically finish the current song/video and then stop, but YouTube and other free content will play indefinetely).

There are pros and cons to this though, on one hand this makes streaming from supported apps much smoother and less strain on the network, you end up getting a better experience because the phone might have a lower quality connection and might be an uneccassary bottleneck. But on the other hand, it might be annoying to turn off if your phone dies and you don't have another device to use to connect and stop the stream.

TV's that can supply at least 5V 1A over their USB ports can power the chromecast directly so you don't need the small but still bulky wall wart, but if powered from the TV's ports you should know that it takes a few extra seconds to come on from a cold start as most TV's don't supply power to the USB ports when off. (Some do, but its not really documented in most online specs). Also, in order to get the best signal its always best to use the 3-inch HDMI extension cable it comes with, (even if it fits without it) as it helps to bring the chromecast further away from the TV's input ports that can give off EMF and mess with the Chromecast's signal especially if you have a shitty WiFi network (Ahem, Airports... Cough).

Overall, I love the little project that Google calls the Chromecast and it works great for the supported apps. The fact that its cross-platform and you can cast from iOS, Android, Windows or Mac, makes it an easy addition to any system big or small. They are constantly improving it and adding new apps and features, (I think the new refresh model has 5ghz and AC WiFi too!).

With the way that people are starting to watch TV, this enables you to watch Netflix, YouTube, Plex, and most cable provider's apps easily on a TV for very little cost, like $30 bucks or so and they always show up with deals on amazon that have $20 Play Store credit included.

So basically just get one per TV, it gives a lot more versatility than putting one as a source on a matrix...