>>22589851 (lb)
That’s an APU fire. The chemical dispersal nozzles are located under each wing towards the trailing edge.
The smoke is from oil not fuel.
You can stand by your assumption if you want, but you’re still wrong. (BTW, I’m a retired airline pilot, 20k+ hrs on Boeings, though not 777). I’m quite familiar with aircraft systems. If you have comparable experience either as a pilot or engineer I’d be prepared to take your opinion seriously, otherwise you should probably just sit this one out. The only other thing that might produce smoke like that would be hydraulic fluid, but the proximity of the hydraulic plumbing to the APU hot section makes it unlikely.