I've decided to revive this thread after going through all my mylists on Nico Nico Douga and revisiting a collection of Idolm@ster MADs I had saved a long time ago. If my memory serves me right, the previous thread didn't last long due to the site's shutdown and a lack of unique responses due to me not really explaining what these are supposed to be.
Idolm@ster was originally an arcade game by Bandai Namco. In the game, you play as a producer, and your job is to nurture your very own idol. It was later released on Xbox (the first game) and PlayStation (the second game, this one is shit).
in 2007 when people initially uploaded their gameplay videos to NND of IM@S on the Xbox and arcade it got incredibly popular and a kind of MAD craze happened around that time and by February 10, 2010 it crossed the 100,000 video mark.
If you don't know MAD/M@D refers to the editing of videos and audio to give them new meanings. This work involves creators using their imagination to transform original works into new creations, differentiating them from straightforward plagiarism. There are many types of different MADs and a video is usually tagged with what kind of MAD it is supposed to be (like Sound MAD, Game MAD, Movie MAD, etc.)
For further information I will recommend you check out these:
https://www.nicovideo.jp/search/アイドルマスター%20MAD
https://idolmaster.tdiary.net/20000102.html (What is IM@S MAD? and a list of popular IM@S MAD videos)
https://metagold.hatenadiary.org/entry/20080513/1210650303 (From a early source if you want more information on Nico Nico Douga in English)
http://kaniblog-eng.blog.jp/archives/1066580690.html#more (Another interesting blog post from early NND user Kanipan which is worth reading)
Since we are approaching Halloween I am going to start off this thread with my most favorite IM@S MAD video which is originally the opening to the anime called Hakaba Kitaro (Graveyard Kitaro), and so what I found really interesting about this opening is that it shows a bunch of clever used colorized cut outs of the original Hakaba Kitaro manga's first chapter which was actually the series that served as a inspiration for the popular horror stories manga and anime series called Gegege no Kintaro.
There is a TV size and full version for this MAD, and I love how for the full he went the extra step to draw bits that were not actually included in the original opening.
https://www.nicovideo.jp/watch/sm11665434 [Play]
https://www.nicovideo.jp/watch/sm11665300 [Play]