Do not ignore post fellow internets!
i'm having this issue, although Airplay Works, the sweet little icon is gone from both Safari and Chrome while watching fullscreen videos. I have to go to control center to activate it. This might seem like a small number of extra steps, but on a iPad 2 this takes about 15 seconds.
Im also lacing the icon on my iPhone 5s, is this a feature or is it done purposely?