Tried the work-around suggested in the post:
"Enabling Closed Captions For Hulu, Netflix And Other Channels" by PlayOn Support (Chris)
Updated : November 30, 2016 23:56 Created : August 16, 2013 12:44
I downloaded visible.mmt and put it in the C:\Program Files (x86)\MediaMall folder and stopped and restarted the PlayOn server but I don't get the video player window that will allow me to turn on CC on Youtube Videos.
I'm running PlayOn 18.104.22.16879 on an Intel i5 machine running 64 bit Windows 7