Many people realize that the sound effects on nature documentaries are added after the fact, since while you can zoom in with the camera is nigh impossible to zoom in with the microphone. But how real is the video?
Imagine that a film crew has been tasked with filming a kangaroo fight. Since the kangaroos won't perform on cue, the crew is likely to spend weeks in the field gathering footage. While they're waiting on males to do battle they may use the time to get close-ups, social interaction shots, or just cute moments involving young kangaroo.
Back at the studio Editors use these various segments to give emotional impact to the fight scene. Editors use these video segments to humanize the animals so that the audience becomes engaged in the documentary.
Even though they are manipulating the footage the end result is that it provides entertainment. Were the video just a stream of facts most of us would lose interest quickly.