How do I airplay to tv from one website, and be on another at same time?

Until I installed 12.0 on my iPad and iPhone, i was able to stream a video from one website to my TV through my Apple TV, and switch to another website or app and chat or other on another website, while the video continued to play on TV.

Since installing the upgrade, I can no longer stream a video and minimize the video, and go to another website without the video switching to wherever I am now.

Is there some setting or whatever I’m missing, or dis the new upgrade eliminate that ability?