Since Google I/O 2012, almost every Google application has had an update. One of these apps is of course the YouTube application. One feature that is not well known about is the ability to preload videos while your phone or tablet is on WiFi and charging.
There is not much else about the feature besides the fact that you can now watch your favorite YouTube videos without the need to let it buffer!
Let us know if any of your devices are showing a pop-up allowing you to turn this on like it did for me.