I've been endlessly frustrated with the MLB's VPN and geolocation systems this year. It seems that in addition to consulting the IP address of the video stream request (as seems to be the case with the web UI) if you attempt to watch over a device (e.g., Chromecast or Fire stick) the IP/geolocation result of your login is also consulted. I had run through about a dozen different working VPN connections on my laptop, yet when switching my network's VPN to the same endpoint, still was blacked out on the device. Only after finding an IP that MLB would stream to the web UI, could I remove the app from my Chromecast, deleting its local cache and auth tokens, and reinstall and log back in.

Haven't seen this explored explicitly yet, as far as I can tell, so a bit of a word to the wise.