Heythe way to grow your prime video business is to make it available on all platforms. Not by banning sale of Chromecast.
You say it's because they don't work with prime video; but that's a problem entirely of your making. You could easily add Chromecast support in your app if you really had customer's interests at heart.
via Stuart Cummings - Google+ Posts http://stu.gs/1FMaGu7