@KalaniB

If you like audio source of your tv connected Sonos room to switch automatically to tv when the tv turns on and plays some audio signal, you should turn on that option. For most users that seem to be very comfortable. 
So if for example a radio stream is playing on that room it will automatically switch and tv sound is playing if you turn ob your tv. 
If the option is kept off you manually have to switch to tv audio within Sonos app. 

If you are streaming music on the sound bar and you want to watch TV, TV Autoplay will automatically switch the music to the TV audio. If you disable TV Autoplay, you will have to manually switch to the TV audio.

Gracias!

Streaming Christmas music on the Arc but want a fireplace video on the screen.

Only time I turn autoplay off.