The Chromecast's playing principle is, if nPlayer sends a file to the Chromecast, playback is done by the Chromecast. Not all videos and audios available on nPlayer can be played on Chromecast but only those that meet the standard of Chromecast can be. nPlayer support all video formats(MKV, AVI, MP4, etc) including H.264 video codec when using Chromecast. Please check the video codec.
Just occured to me, I think the original CC1 supported AVI, its hardware was mostly identical and it had a lot more cache ssd on board. Guarantee it had a lot of limits on file types and codecs though - if he did mean a CC1.