METROTube for Windows Phone 7 will include a pre-loading feature for offline viewing which is already available on METROTube for Windows Phone 8. This isn't the first time that METROTube lost connectivity thanks to YouTube and had to rejiggle things. In the U.S., you can purchase the METROTube app for 99 cents from the Windows Phone Marketplace. If you love watching YouTube videos on your Windows Phone handset, this is a must-have app which you can buy at the sourcelink.
source: METROTube via WPCentral