“Point of No Return” is episode eleven of season four of Stargate SG-1.
General Hammond calls a meeting with SG-1. They have received a call from a man who sounds like a standard conspiracy theory nutcase, except that he knows about the stargate and where it was discovered, and he wants a meeting with Jack O’Neill. He knows far too much that is actually true to be your standard conspiracy nut.
Jack meets the man, who seems a bit crazy as well as being convinced that he’s an alien, and suggests that his description of the stargate programme would make a good television series. The man, Martin, knows rather a lot about the actual stargate programme, and bits of history connected to the stargate.
Although I haven’t seen this episode before, I have seen the man in it from the chunk of episodes I saw from around season five or so. Martin isn’t as crazy or as paranoid as he might seem.