Assuming the video description is accurate (it is chemically plausible, in any case), this was a hydrogenation kettle that was unintentionally purged with room air instead of nitrogen after a reaction -- the residual ethanol vapor from the solvent in the kettle mixes with air to make an explosive mixture. As for ignition, the Raney nickel hydrogenation catalyst is pyrophoric, and even spent catalyst can ignite on contact with air. The kettle was being washed out with water through the access port, but the mixture still flashed.
With regards to the worker, I don't think there's any chance that this was survivable. He's out of view in about six frames, and that kind of acceleration is likely to be fatal even before he hits the ceiling or other machinery.
Edit: Just noticed something -- around the 10-second mark, there's a big patch of light that suddenly appears between the third and fourth kettles. I'm thinking this is sunlight from a hole in the roof, and it's where most of the debris falls.
Double Edit: I found the accident report (using google translate) -- this was indeed a hydrogenation reactor (for converting p-nitrophenol to p-aminophenol), and there was one casualty.