Suddenly it's been happening in every single chorus out there: At a climactic line of the song, the original Vocaloid will burst in. http://www.youtube.com/watch?v=_DTD_7x7A38
are just a few examples. I've also seen it in choruses of Coward Montblanc, Cantarella, "Eh? Ah, Sou", Torinoko City.... it goes on and on. This is slightly more specific than just using the original Vocaloid; it's how they have a solo, usually right before the last chorus or oaired choruses.
The question I'm leading up to is, does Nico Nico have a convenient Japanese term for this? Anything that happens this often usually gets one eventually, like "omaera no ai de mienai" for when a video can't be watched with comments on due to how many there are. The closest I've seen is that these sorts of things are commonly prefaced by "zawazawa", but that has other usage, so... yeah. Anyone have an idea?