If I’m calculating things correctly, there is a problem with the file:
00:28:19.403 T:3609195264 INFO: ffmpeg[D71FF300]: Duration: 00:20:51.29, start: 0.000000, bitrate: 399 kb/s
00:28:19.403 T:3609195264 INFO: ffmpeg[D71FF300]: Chapter #0:0: start 0.000000, end 80.623000
00:28:19.403 T:3609195264 INFO: ffmpeg[D71FF300]: Metadata:
00:28:19.403 T:3609195264 INFO: ffmpeg[D71FF300]: title : Opening
00:28:19.403 T:3609195264 INFO: ffmpeg[D71FF300]: Chapter #0:1: start 0.000000, end 1251.333000
00:28:19.403 T:3609195264 INFO: ffmpeg[D71FF300]: Metadata:
00:28:19.404 T:3609195264 INFO: ffmpeg[D71FF300]: title : Main
00:28:19.404 T:3609195264 INFO: ffmpeg[D71FF300]: Chapter #0:2: start 0.000000, end 70.863000
00:28:19.404 T:3609195264 INFO: ffmpeg[D71FF300]: Metadata:
00:28:19.404 T:3609195264 INFO: ffmpeg[D71FF300]: title : Ending
According to that, the video is 20m 51s long, however if you look at the chapters, they add up to 1401 seconds which is about 23 minutes. That seems to match with your comment about ‘cutting out several minutes early’.
Of course I could be wrong about how to calculate the chapters properly…