About the SABC I don't object. No one films a documentary and later decides, i'm going to sell that to BBC. In most instances a documentary is commisioned by the broadcaster. Once it is filmed it is then subjected to scrutiny and aproval by the broadcaster before it can be aired. Like I mentioned before every broadcaster has an agenda of some sort. It might not be a written policy but it is usually implemented (in practice) through the aproval and the commisioning processes.
The SABC blacklist is a very good example of an agenda that was threatening to become written policy.