This is a joke, right? If it requires a Raspberry Pi then it is not different than Kodi or wherever else that supports the same functionality. I feel like the authors here reinvented fire and then are refusing to acknowledge or admit that it has already been done.
First, that isn't how Chromecast works.. however, for me to cast a movie from my laptop to Kodi I just enable file sharing on the directory that I want to share and then I can access it in Kodi and play it using the remote. I can also serve it via HTTP or SFTP.