You can see the videos on thoughtmaybe are BBC watermarked. AFAIK, the BBC never released them outside the UK, although this is mainly due to copyright and the special provisions the BBC has inside the UK that enables them to produce such high quality material. So while they may be "freely" available, I doubt it's legal. I'm not sure how much the BBC cares about enforcement.
adam curtis has implied (in the chapo interview linked in this discussion, i think) that he encourages the bbc to/has an agreement with them to avoid taking down uploads of his films
