Unsure I can be bothered to watch it all, but the answer to your question came quite early on. Socialism isn't communism, socialism is this warm, fuzzy, and good policy which looks after the poor, makes society fairer, and stops the workers being abused. Some may see it as a stepping stone to a more extreme position but that would just be their aim, a long way off and unlikely to occur. It's not what they can push for at present nor implement in a single term, so why would they claim it is what they're presenting offering ?
The present situation is a simple case of a right winger gaining control and swinging the party way to it's right, then when let go it swings back way to the left for a while. It'll dampen down nearer the centre in it's own time.