I found no setup instructions where audio from an external source was feed to the Apple TV and to your airpods. In other words, something someone would like but wasn't designed in.
Now some TVs will connect to the airpods. https://discussions.apple.com/thread/7832159?start=0&tstart=0
Hi. I have a samsung ks7005 tv and a apple tv 4th generation. I want to connect samsung tv audio to apple tv and then connect my airpods to apple tv so that I can hear tv audio on my airpods?