That is probabily the largest collaboration of anime OPs ever.
And I learned so much from that video. By watching it repeatedly, I was able to find some of the most amazing anime I have ever seen, including Air, Haruhi, and Bokurano.
There are several different songs in the same series as follows.
Kumikyoku Nico Nico Douga (the first)
Nico Nico Douga Ryuuseigun (the longest, and probabily best)
Nanairo no Nico Nico Douga (the newest, as far as I know)