Officially from Support:

Light BDSM is allowed. No choking, no rape themes, you cannot break the
skin. If you are going to use wax make sure you are not causing blisters
and stay away from red wax since it can look like blood. If you are
going to use ropes make sure it is not around the person’s neck and that
they are not tied so tight that they may break the skin.

It is a
fine line so usually we say to stay away from it.  Just keep in mind, whatever
is happening on camera cannot violate obscenity laws and cannot cause
harm to the others who are partaking. 

If you wish to do a BDSM show, please contact Support FIRST to inform them what you would like to do as normally BDSM shows are not allowed.