FYI, i already play youtube video using XIbo Player for Windows,
And as far as i know if we using Xibo Player For Windows, it was based on .Net.
Regarding to development progress on youtube,
and after i made several testing , it seems Xibo Player when playing Youtube need some of part IE 11 library
So .... perhaps if you can upgrade your IE 8 to 11 on windows 7 , maybe it'll be works