obscenity laws are more state issued than federal. they also have to follow other countries' obscenity laws too. if they fail to do so, they are likely to be blocked. check out uks porn laws. they are fucking insane because the english are uptight.
We have the "Obscene publications act" which bans distribution of material "likely to deprave and corrupt", and we have the Criminal Justice and Immigration Act which bans posession of "extreme pornography" (this is a dreadful law). The decision about what constitutes either obscene or extreme material is in the hands of a jury, not of a judge, the CPS (that's the public prosecutor in England and Wales), or politicians.
It has been established in
R v Peacock that anal fisting (man on man, in this case) is not "obscene", though the CPS prosecution guidelines have not been updated to reflect this. I'm pretty sure the CPS had a go on it being "extreme" as well and failed. The problem with squirting is that to distribute a video you have to have a BBFC certificate (just like the certificates on films) and you can't get one if urination is included, and the opinion of those issuing certificates is that "squirt" is pee. Only one has ever been issued for female ejacutlation and the producer (Anna Arrowsmith, aka Anna Span) turned up with a load of evidence which convinced the BBFC to grant a certificate, but it did not cause them to review their general stand against it.
Video on demand services are going to have to comply with the same restrictions as on video supplied on physical media, so the same banned list. As noted, a jury in the criminal courts here have found that fisting can be portrayed on video, so MFC / CB rules are in fact stricter than English law in this instance. That doesn't mean the law here is sensible, it isn't, it's iniquitous, it seeks to outlaw portrayl of many legal acts .
We English aren't uptight, but some politicians are and some are so afraid of the Daily Mail, which is incredibly uptight about sex (despite the lurid sidebar of shame) and seems to strike fear into politicans. More than anything, this is an area where sections of the media dominate the politican agenda here