I understand that Plex does not currently support streaming device downloaded Plex videos through Chromecast. Long term, that would be a valuable feature to implement. However, with a minor code tweak to the existing client software, we could improve the overall user experience.
When the user requests to stream Plex to Chromecast, just ignore the download cache and stream from the Plex server.
As a workaround, the user has to manually delete the download cache, which is inconvenient.
