The male lion at the Henry Doorly zoo in Omaha, Nebraska wants to play with the kids behind the glass. (before critiquing too much, read more below)
Added: I am only taking this video. I'm not speaking in it nor am I encouraging kids to "do it again" and what not. I don't know who Emma is or her family. I don't know who the lady is who said "tiger". I agree with what most of you have said that the lion is happy to have the interaction and is merely playing with the people on the other side of the glass. If he were annoyed, then he would have just moved. I also agree that it's not nice to tease the lion as well.