A bunch of old IMAX documentaries used to be on Hulu, but this colorful concoction was the only one left, and now it's gone away, too. Presented by South Korea's Ssangyong Corporation (now GS Group), Adrian Warren's film is impressively photographed albeit a bit unfocused, as it begins examining plant life, then branches out to explore symbiosis with the insect and animal kingdoms, before encouraging viewers to do their part in protecting them. Although the environmentalist message is as blunt as a contemporary Captain Planet episode, it's wholly appropriate in this context, and it's served with less doom n' gloom than in more artful pieces like Koyaanisqatsi or Baraka. If I remember correctly, 1990s audiences could view The Secret of…