both points of the flag are garbage, image quality takes a hit for non-hd reuploads and the looping is synchronized, I can't see anything wrong with it aside from it being a short loop..
So image quality takes a hit for being non-hd reupload? That seems to prove it's pretty poor quality. and the looping is bad because it's 'choppy' and unnatural looking, not because of length. Also that's a third party watermark I'm pretty sure, assuming the 'artist' didn't produce this hentai.
The coloring style matches up with many of the artist's other posts, so I think it's safe to say that it's original work. Otherwise, the points brought up against it are valid.