Video - Leopard playing with Impala calf - an odd behaviour or just a food ?

I came upon a viral picture and saw this where an baby impala is standing beside a leopard while looking at other elder impalas standing at a distance, at first it looks like funny or cute as both seems to be friend. Here is the image below :

http://i.imgur.com/bHIneon.jpg

But the truth is completely different, I went upon finding the video from which this screenshot was taken and turned out to be that this impala calf was just a food for the Leopard. Here is the video if you want to see :

https://www.youtube.com/watch?v=yJpT-72gveA

I have not done any research on leopard behaviour but from what I know about feline is that this was nothing odd, leopard was pretty well aware that this calf will not run away so he was not in hurry to kill it. It is also said that Leopard, Cheetah etc. won't eat their catch right away, rather they take rest and only after getting back their breath, they eat it. So I think it was similar case here. May be he was not just that hungry.

But will love to know more about this behaviour of the leopard.

This is a very sad video. I wish it was really two friendly animals instead of a pray and predator :(

Very nice video first time I have seen this type of behaviour from a leopard.

Brother, that is sad. But I can easily relate this behaviour to cats because I a cat in my childhood. I saw it playing with mice few times.