what is that or more accurately what was it...?

Observing and encountering apex predators is a lot of fun and no two interactions are the same and you never truly know what it is you will witness these amazingly intelligent animals do. Marine mammal hunting orca aka Bigg's orca are somewhat incredible, unpredictable and can be greatly dynamic.

From time to time you get see things like this...

Some consider it to be their playful demeanour, which can be slightly confronting - especially if you like what it is they just killed and tore to pieces so they could consume it. However, it is a unique behaviour to play with their food and almost present and show it off in such a manner.

So why? Why do they proud around a carcass of an animal they just hunted and ate? I believe it is for a variety of reasons and no two displaying acts are for the same reasons. As these animals are highly mentally developed and do have unique individual personalities, so as a result the reasoning would be just as diverse and potentially complex.
1) An act of being proud - simply a behaviour as if to say look at what I caught.
2) The adrenaline of the hunt has not quite worn off and the playing of the carcass might be due to them still being in a highly agitated state from high energy that comes from the hunt.
3) A younger orca playing and practising various techniques of moving or becoming familiar with their prey - building their repertoire of movements to feed and forage more efficiently as they become older.