Wow you actually found a clip from one of those videos?
GIGA for freaks is a huge collection of live action heroine fetish/fantasy JAV porn.
http://www.giga-freeks.net/
Most of it is the usual bondage and humiliation and lot of it looks ridiculously awful. However there were two or three that actually look interesting such as the series Brainwash Heroine.
Here's a few samples. I don't know if this stuff actually gets into any physical or personality (or the typical costume change...) transformations. I believe its simply mind-control.
http://nakaama.web.infoseek.co.jp/dvd/thunder_girl3.htm
http://nakaama.web.infoseek.co.jp/dvd/tuyorenjer.htm
http://nakaama.web.infoseek.co.jp/dvd/bird5.htm
By the way if this site has been posted here before I highly recommend people explore it. Lots of stuff from both East and Western movies, manga, and anime (MC, Evil Con, TF, Vamp, etc.) I've gotten some great leads and info from it.
http://nakaama.web.infoseek.co.jp/