Q: Airplay directly from youtube in safari doesn't work!

Hi, one of most usefull things on apple tv for me was direct airplay from youtube in Safari, but now with my ATV4 it doesn't work!  Airplay from itunes, photos, facebook etc on mac work perfectly even on ipad and iphone, but as deliberate only thing I need doesn't work please help

It look's like everything is working - airplay in menu bar is blue and sometime gray screen with airplay appears for 0,01s but it plays still on mac not on tv.. when I had ATV3 it worked but everytime when I turned on Apple tv and connected connected airplay from safari youtube I needed to make a move in playback bar (go forward) but then it worked normally.