Hi Jim, I cannot get YouTube/tv to play in JRiver either. All of the other streams work perfectly. I do have a paid subscription, and when I open the YouTube/tv stream, it indeed appears to have signed me in because I see all of my preset choices (Library, etc.) Additionally, all of the choices have thumbnails that have active video in them, just like when I play it through my browser.
When I click on one of the thumbnails to play it however, it expands to full screen, and I get the loading circle, which is turning, but the stream never loads. I did try the Ctl-click, but that didn't help.
In answer to your question, I am only interested in playing this through JRiver if I can get all of the video processing activated (MadVr, etc) so I can engage Madshi's wonderful up-scaling choices. I am hoping the combination of his efficient algorithms plus being able to hardware accelerate, will help smooth out the stuttering I get with YouTube/tv sports presentations.