Stephen, I won't answer concretely because I don't have the answeres, but can suggest given your interest, you might want to continue by googling independent producers' "terms of trade" and "video on demand rights" for various countries, and also explore through any independent filmmaker unions, where you are involved (Is there one in Belgium? If not, if you can handle German look at AGDOK's website, and the UK's PACT ). Electronic media rights are a hotly contested issue. "Should" concede is different from "do". Your questions are clear but the answer can be very complex and depend on territory, it seems to me. I have no knowledge about the US, please note.
"Terms of trade" are just the rules of the game, as agreed by participants,where the percentages and timeframes are spelled out across a sector of the industry. In the UK for example, terms of trade were recently agreed between PACT (indy producers/directors) and various public broadcasters. If you are in Belgium and working locally, my guess is you really do need to talk directly with your more experienced colleagues working in the same market.
Maybe see if you can access the European Documentary Network's magazine, DOX from this fall. I wrote a piece about VoD rights for them and you will appreciate the companion pieces in the same issue that were extracted from other sources – especially a compact version of the PACT agreements (really useful if you are new to the topic). Try EDN on-line. Good luck!