Edit 2: So it appears the movie is available on KissAnime, you can watch it here: http://kissanime.ru/Anime/Mazinger-Z-Movie-Infinity (and yes, it seems my IP is no longer banned from KissAnime, just gotta be careful not to log in to my account or use the site while ad-block is active).
The only benifit of making a kiss account is to be able to download videos, that and to leave comments like on youtube, but not many people use accounts there anyway and after my experience I don't recommend it, there are other ways to download from kissanime/kisscartoon anyway.
The only benifit of making a kiss account is to be able to download videos, that and to leave commen