I opened Chrome on my desktop computer selected an Amazon Prime movie, then clicked cast and the movie played fine on my big screen tv. I will admit that I have a 20 mb Internet connection, but I am assuming that the movies play fine on your computer. One thing does come to mind, if your computer is connected by WiFi to your network, try plugging it into one of the ethernet ports on your router. I will test mine with a laptop on WiFi later.
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