A couple of points...
The triple chime that repeats about every 30 seconds is likely the Lav Smoke Detector Alert and not the cockpit-to-cabin call. Note that it sounds on a regular cycle, including during the flare.
There was a possible turbine burst - based on the reports that schrapnel hit the fuselage and cowling parts were found on the ground. I did hear internally that a fuel line burst or was cut, causing the fire to take longer than expected to extinguish. In my opinion, this alone could have primed the Captain to tell the flight attendants to prep for possible evacuation. Add in the smoke in the cabin and I can understand the Evac mindset during the 13 minute flight. A lot was happening in a short time.
Once on the ground, the PAs don't seem to match what was being told to ATC. This is a head-scratcher. There is clearly a PA telling the flight attendants to take their stations, then the Easy Victor call. (That's our EVAC command and we all know it's archaic and confusing.) Once started, it's extremely difficult to stop an evacuation. Based on the selfie-video, I don't see any evidence that the passengers were panicking or opened an exit before the Easy Victor call.
All in all, kudos for the crew for getting on the ground quickly. The NTSB and FAA will have a field day with the video evidence of how effective the company procedures are.
Personally, I am quite unhappy with seeing the passenger response and lack of true command of the cabin. Seeing the lack of reaction from the passengers as they were more concerned with turning on their cellphones and taking videos tells me that we need to adjust our culture and make sure there is no ambiguity when the Evac decision is made.