"I'm not sure I can really believe or trust the information I receive from such documentaries or those aired on PBS. "
not sure? I think the point of the segment is that you definitely can't trust ANY nature documentary, if even Richard Attenborough (I refuse to call him sir) lies. And even the guy who teaches people about those kinds of films lied and said that it was IMPOSSIBLE to make true nature films.

"Where does one look for documentaries of truth?"
Why does one NEED to look for nature documentaries? If you want to see the natural world, look at the birds, squirrels, foxes, possums etc in your own neighborhood. We have a virginia possum near our house and I love seeing her once in a while and I'm looking forward to maybe seeing her with her babies int he spring, if I'm lucky.

But I would never DREAM of interacting with her, or of trying to get her on film.

The belief is that these nature films expose us to nature and make us more aware and perhaps more compassionate towards the natural world, but considering the extreme cruelty of our society towards the natural world, and that the perpetrators of these cruelties are people who were raised watching nature films, and going to circuses and zoos, I think it is obvious that this belief is false.

These nature documentaries cause us to believe that animals exist for our entertainment and make us more cruel towards the natural world and its inhabitants.

And this video only focussed on animals in film and did not even skim the surface of animal horrors in the name of entertainment.
animals in circuses, roadside zoos and the like are even worse off.
plus there are a huge number of breeders who sell exotic animals to individuals and the cruelty there is horrible!

Fopr example, did you know that all birds are first generation? Which means they are caprtured in the wild and sold to pet shops. So anyone who OWNS a pet bird is commiting the most basic form of animal cruelty (as Jane Goodall explained) that even if they personally treat the animal "well" the fact that the animal was kidnapped from his natural habitant, from his family, and often from his mother and then transported and sold is within itself abuse.

if you want to have a relationship with an animal, go to the local animal shelter and rescue an animal there. Learn about the species as much as you can to make sure that you treat the animal as "well" as you can.

(I put well in brackets because we can never know if we are treating another species with whom we can not effectively communicate well, we can only approximate good treatment as much as possible)

and if you want to see animals in their natural habitat, look in your own backyard. If you want to see exotic animals, move to a place where they live...but I would not recommend going looking for them in the forest, that is not YOUR place.

As for those intimate private moments, well just like we would not want a camera crew showing up in our bedroom while we are sleeping or having sex (well some may ;-) but most certainly won't) the same is true for another species. There are things that we are not meant to see or know about. And claiming to do it in the name of research is bullshit.

We do not need to see polar bears breeding or foxes inside their den.