There are a lot of topics on how to use the raspberry pi as an Apple TV or Chromecast. I am looking to send the output from video playing on the Raspberry Pi to a Chromecast or Apple TV.
A bit more detail would probably help with this one but it sounds like it might be a job for Plex - you'd need your mobile phone to initiate playback to the Chromecast but it's more convenient than a keyboard and mouse.