https://www.bbc.co.uk/news/av/embed/p07vtml5/50525134 Scary event, engine surging or bad bird strike, I saw something like this on a flight one time as we were coming down into Amsterdam on a 737 very scary, but this looks a lot worse. (you need to click again on the image to play the video, I can't embed this one)
It could be lack of decent maintenace leading to extreme engine fatigue. I am glad that it came to a safe landing. Kudos to the pilot.
A quick search comes up with "at least 3 hours" or over 2000 km, I don't fancy it all that much either I mentioned my own experience of seeing a compressor stall flame shoot out the front of the right engine of a 737 on approach to Schiphol airport, I was looking out the window at the time with my camera ready to take a picture of the sunrise when the bird strike happened, I nearly jumped out of my seat there would have been a flame coming out the back of the engine as well but being a single bird event the engine recovered and didn't repeat the stall, we were actually a lot lower than I thought as the cloud cover was really low and it was foggy on the ground and we were on the ground within two or three minutes. When it happened the stewardess came over and asked me what I had seen as I had uttered a profanity and she went back and reported to the flight crew on it, she later came back and told me that in her 20 odd year career that was her first bird strike event. There was another time when coming back from Poland on an Easyjet 737 we were just circling over the Wirral getting ready to descend for the final approach into Liverpool and there was a huge bang from the left engine, we were seated just in front of it on that side, that engine sounded really sick from then on until we landed, as we got off the engine was still rotating and sounded like a bag of marbles in a washing machine it was a really sick engine It was surprising that so many people were able to record so quickly what happened on this PAL flight, both on the ground and from within the cabin.