This Game of Thrones voice-over proves a few things. One of these things is that Jimmy Fallon knows what's funny, another is that little kid voices can take the menace out of anything and finally that Games of Thrones is epic no matter what.
Fallon has taken over the Tonight show and has it running at peak performance. He has his finger on the pulse of what's hot and what's not, and given the fact that Game of Thrones is always hot and any iteration is an instant classic these voice-overs are perfectly in line.
We can't give Fallon all of the credit though, as the idea came in from a suggestion box that Fallon tends to use some of the time.