im trying to understand how airplay works with homepod... itunes is fine and works from its own airplay icon as usual. however i assumed it can play from youtube etc/system audio (maybe not the feed back effects) on a mac since its choosable as an airplay speaker from the title bar. when you do this you get no sound. if this isnt supported what is it there for? alternatively, even in safari youtube has its own icon for airplay, when you click these it says no devices found. i assumed since on the homepod specs it says under sources 'airplay speaker from ios/mac' that these would work?