This footage is of regular clouds, despite the breathless commentary in the video. Details here:
https://www.reddit.com/r/interestingasfuck/comments/110nlai/...
The derailment is, no doubt, a serious public health crisis. However, it helps no-one to spread misleading videos and commentary.
The wave of panic in the thread you posted is a stark example of "fake news" in action. A sign of the times, I suppose.