This looks to me like some sort of structural failure (corrosion?).
Screenshot from video.
No widely scattered parts as I would expect from an explosion, and no discussion of a fire except from the flair stack.
Large cooling towers seem simple and massive. They require a surprising amount of attention to little relatively inexpensive tasks to get the intended long service life out of them.
Getting the water chemistry program incorrect could have this result, as could a water distribution header joint separation.