But you can't "cast" from Newpipe (you'd have cast the phone's screen and play stuff in Newpipe in your phone). Which anyways is what I do when I start getting too many ads (typically I just shutdown the TV and try to time turning it back on so the ad is finishing. it's something of a mini-game).

EDIT: I'm referring to the original chromecast, not the new "Chromecast with Google TV"