93 seconds from when that recording starts to when the camera hits daylight. Evacuation couldn't have started much before then.
As for the fire, even at the end of the trip, there's a lot of fuel and very little metal. Not even the 777 is designed to protect its contents from a fire of any significant duration or intensity.
With regards to overhead bins, you just can't win. Sure, you can make an announcement on the P/A, but even in the best of circumstances -- native speaker to native listener, perfect sound reproduction with normal background noise, no 400-Hz buzz -- the message is not always resolvable. The more complicated, the harder it gets. Really, if you can get "Evacuate" across, you can't hope for more. Now, add in all the things that go wrong with an airline P/A, and it's foolish to even try.
As for the folks in overhead bins -- there's probably a knock-on effect too: the aisle is blocked, as the person ahead is fishing in the bin. Might as well grab the bag, right?
What happened? Dunno. Flightradar24 has put online their ADS-B data in a CSV format, and they seem to be suggesting that it involves hitting a low altitude (GPS or unadjusted pressure?) of 475 ft, then going up to 600 before settling in at 525/50 (granularity seems to be 25 feet) after 16 seconds.
They could have balked hard. Not AC 621-hard, but hard enough to settle back in. We'll find out.