The video has since been reinstated after the artist, Mykki Bianco, appealed against the decision. likely the initial banning of the video has simply created more publicity for it.
The picture/freeze frame above is the reason, and honestly it's just a flash on the screen for barely half a second. If you weren't looking for it, it'd be easy to miss.
Bianco comments on Billboard:
According to Blanco, who posted a screen shot of the "image in question," YouTube took down the video because it shows a man's "bulge."
As Blanco and others were quick to point out, there are many videos on YouTube that show just as much or more explicit material but are acceptable because they align with heterosexual standards of sexuality.
"Why is Queer sexuality censored & policed but images for a Cis male gaze of sexualized women are not ?" Blanco tweeted.
Blanco also said there had been a "social media produced comment thread" where someone said the video had an image of a male "scrotum" -- an erroneous claim.
"Our society grants hetero privilege to parade overly sexualized images of women for a cis male gaze yet Queer imagery is policied, demeaned," Blanco tweeted.
Now the video is back online but with a "content warning" that requires viewers to sign in to confirm their age before viewing. Billboard
Compare that to Kylie Monogue's "Slow" for instance:Why is Queer sexuality censored & policed but images for a Cis male gaze of sexualized women are not ? @YouTube pic.twitter.com/JSH7pc3YVt— MYKKI (@MykkiBlanco) December 2, 2016
What about Kylie's "All the lovers"? She's a straight friend of gays, but she's straight.
Kylie Minogue - All The Lovers (2010) from bibitoto xue on Vimeo.