If it was Cosmos, I think I remember the same. Except, what he was saying is that we had discovered within the last decade (at the time of filming, the 1970s) that this was NOT the case. When he was talking about Venusian jungles, he was referring to what people once speculated.

I may be wrong about that, I don’t remember the year in which Russia got that lander onto the surface. There is a big focus on both versions of Cosmos in illustrating how old ideas have died out in favor of new ones, however, so he and Neil both talked about past incorrect hypothesis all the time to contrast them against what we know now.