Do you have a "Smart TV"?
The icon in the yellow circle is the "CAST" button and the pink one is the "Airplay" button, see location 2 on the page screenshot. It will only appear if: (1.) you are able to send the video to your smart TV, and (2.) if the broadcast stream has already started.
It can operate from your smartphone, tablet or computer as long as you are on the household network or WiFi.