Earlier quoted context omitted.
a) You have copyright on your work. That means you own and retain the right to distribute it or not, and importantly this includes a notion of moral rights. b) A forum is not a collective work; it is a privately owned publishing vehicle which may be selectively edited or change hands at any point.
c) You sign terms of service granting rights to the publishing vehicle.
good point, though I believe publishing contracts need limited terms to be enforceable and that you don't grant reproduction/distribution rights in perpetuity