I just have to question these types of apps, especially on Windows RT.
Internet Explorer 10 has Flash support, with google services and YouTube being supported. On a 10.6 inch screen, with a Flash enabled browser, that makes the need for a YouTube app, facebook app, and other apps like google maps a tad redundant. It's more of a nicety than necessity.
I can pin facebook onto my Start Screen, BAM! Facebook app! Using the facebook site with a touch screen isn't too difficult and more preferable than a limited facebook app.
I can pin YouTube to my Start Screen, BAM! YouTube app! WAY better than using dinky YouTube app or the dinky mobile version of the site on an ipad.
So on and so forth, ect, ect, ect.....
Point being, Flash enabled IE 10 makes the need for certain apps pointless. The point of having apps in the first place is to take a Desktop version of a website and condense the needed parts into a touch friendly, handheld version. Been that way since the iphone, been that way for android, and Windows Phone. Been that way for android tablets and ipad since they're running the same OS as the smartphone counterparts, and therefore have to use those apps to access the same content where it would be a click or tap of a IE pin or bookmark to access the correct version.