AirPlay on HomePod / HomePod Mini

I have a question concerning HomePod / HomePod Mini and more specifically AirPlay. I've never used this feature, and I read on the web that we had to launch a YouTube video (for example) before turning AirPlay on to have the sound coming from the speaker. Does it mean AirPlay has to be reactivated for each YouTube video? or once it's turned on from one YouTube video we can directly change the video with the sound still coming from the speaker without doing anything?

Thanks in advance