It is an animation and your HD tv (or blue ray player) can upscale it nicely without loosing definition. It will smooth the edges a little and you loose some information in the process.
Now do that with a DVD of a nature program, compare it to a Bluray and a 4k version. Did some in store with Sony mastered safari clips, there is a nice difference. HD is a sweet spot, and 4k is nicer, but not a requirement just yet. SD is a blurry mess in comparison.