No sounds when watching youtube video

I have an optical cable connected to my Philips Soundbar. 

My WDTV Live (new model) is set up to play sounds via optical passthru with all decoding selected.

No sounds when I play youtube videos.

No problem with my older model of WDTV Live unit.

Please advise

And if you change from optical passthru to Stereo, do you have audio?