[michaelmachine]

There is a video available here as well:

https://www.youtube.com/watch?v=Gtf-1JibORg

[londons_explore]

Those videos show surprising 'hotspot' lines - I would expect the plasma to be far more evenly distributed.

[lambdadmitry]

Because really hot plasma doesn't emit in visible range, it's all x-ray, so what you are seeing is it's (relatively) cool edge. It might have colder regions, but that doesn't necessarily mean that the main volume is unstable.