The point is that any movement like XR that focuses on green reform of capitalism is ultimately doomed to fail (or a dead end, as the video puts it) because a system based on endless growth is inherently at odds with environmentalist goals.
I know very little about XR, so someone please correct me if I'm wrong, but my guess is that most people involved with XR (especially in senior positions) fully agree that "an economic system based on endless growth is inherently at odds with environmentalist goals".
Surely the decision to focus on driving green reform in the existing capitalist system is a strategic decision made on the grounds of expediency rather than an implicit acceptance of neoliberal economics? If we are to avoid catastrophic environmental impacts we need to see action now. Action now needs public support and engagement and I just don't think that people in countries like the UK are ready to accept or embrace radical economic reform yet.
Secondarily, it might not be a foolish thing to disassociate economic reform from an environmental agenda. Living on a healthy planet is something that I think is more widely palatable across a diverse political spectrum than a revolution to the economic system. Focussing on the environmental side of the debate may well be a deliberate strategy to avoid it becoming highly politicised (the environment is always political but I mean politicised in terms of becoming an issue of bipolar partisanship in government).
A socially just and healthy planet absolutely require economic reform, the two issues go hand in hand, but my suspicion it's better to campaign for them separately?