I agree somewhat with that kids' theory, but I'd that were truly the case then there would be other videos like this that had so many views. And the frozen video being so far away in the list makes me wonder.
Could also be that the video is embedded in a site or sites and on auto play?
Frozen won't have anything like as much appeal to young, barely lingual children, who know that they like brightly coloured cars with faces, can probably say "cars" to their parents, and who will watch a video with those cars from end to end and will then immediately watch it again.
Just as young children seem to have an endless capacity to watch the same kids' DVD over and over again.
This is far from the only example on YouTube - there are thousands of simple videos that get staggeringly high view counts, which become "fascinators" for kids. I saw one not so long ago which was literally just someone playing with a Play-Doh set. Nicely shot, no dialogue, just two hands making brightly coloured food-shaped items out of Play-Doh. Millions of views, right there.
Could also be that the video is embedded in a site or sites and on auto play?