Oh gosh, thanks for that. My little girl is "probably" autistic (speech and language therapist suspects, but not confirmed by psych. yet). She is 3 and a hald and really loves being with other kids but just doesn't "get" the whole playing thing. Mind you, neither did I as a kid and I've learnt over the years how to, but it's been hard and I still worry. I'm apparently NT.
It is really frustrating as she plays physically and non verbally with other children, but of course the ones that do that at pre school are all boys, and they are very noisy which triggers her noise sensory issues. So she get's stuck both ways. She is starting to mimic adults laughing and things like that, which is, well just whatever it is. I'm trying to talk to her about sad/happy faces but I find it quite hard myself.
The other kids were quite patient in that video, but we didn't see what happened when the camera's weren't there. It's a shame they weren't able to share more, I think that large class sizes like that can be quite frightening even for NT kids and make them less likely to share or be compassionate.