Why is Apple TV on my MacBook Air so buggy?

When I bought my MacBook Air last year, I got 1 year AppleTV free trial. I just canceled it because the experience is so thoroughly frustrating. For instance, why can I not play something on my AppleTV app on the Mac and show it on a large screen attached via HDMI? I can hear the sound but the screen will be simply black. Even running it only on my Mac, I repeatedly encounter a stuck image (or black screen) while the sound continues. This happens with downloaded as well as streaming content, and usually renders the entire Mac unstable (cursor disappears), requiring a restart. Is this something others have experienced as well?