HBO Go, FXNow, FOXnow, Starz, and a bunch of other apps just won't work for Comcast subscribers like me. If anyone else is pissed off at Comcast for blocking Android TV but not Roku or Apple TV, file a complaint here: https://consumercomplaints.fcc.gov/hc/en-us (I filed it under internet, but it might go under TV too).
EDIT: To be clear, Comcast is not blocking the services themselves. Comcast is not allowing their cable subscribers to log in to their Comcast account so they can use things like HBO Go on Android TV, even though it is possible on Apple TV.
time warner also doesnt work with fxnow or fox now