Access Internet Through Bridged MacBook Connection?

I'm trying to access the internet through an Ethernet connection bridged through my MacBook, which is accessing the network through a WiFi connection.

So, I've logged into the wireless network on my MacBook, and accessing the internet normally. I then turned on sharing my internet connection from Wifi to internet in system preferences.

The Apple TV is in a room that does not have wifi access. So the solution I found was to run a known good Ethernet cable from the MacBook into the the other room and connect to the Apple TV.

The Apple TV instantly recognizes the Ethernet connection and has populated the IP address, and other network details. All looks good, however the Apple TV does not access the internet.

So, I'm not sure what I need to do. This should work, right? Perhaps I need to manually open a port on the MacBook to allow the Apple TV to access the network?