avi does work with this encoding
I was messing with this yesterday, I couldnt get a film to cast, I tried solid explorer cast & all cast & video stream from my pc (last 1 loaded but was unwatchable). I dont have root on the chromecast. So I found 1 .avi film worked and 2 didnt. Upon inspection of encoding of the video and audio INSIDE the avi files, I found it only appears to support x264. Also framerate below 30, bitrate below 6000 makes it watchable (that might be because i have an older ovation tablet). As for audio I was using aac (any bitrate upto 256). Also I had it set on high quality video, which in anyvideoconverter means lower compression and larger file size. Once in that format, it would cast perfectly from any app, pc or mobile.
<6000 (and inc.) video bitrate
<256 (and inc.) audio bitrate.