Only the eagle-eyed will spot a fake...
Interesting to see that - in the wake of all of the sexing up floating about at the moment - someone's blown the whistle on the way that dear Auntie has been manipulating the truth for years.
Seriously - watch closely next time, and see if you can spot where disparate shots of different animals have been pasted together to create a 'story'. It's the anthropomorphic drive coupled with the need for entertainment and narrative in information-based programmes.
Of course, the real trick is spotting when they composite footage, or add CGI whales. Harder to spot than you'd think in undersea documentaries, becasue of the different way that masses behave in water. It gets over that 'feet on the floor' weight issue you get in so much CGI.