I have tried this on two Macs and at different scale and enhance settings, sometimes the output is 60fps instead of the original 24fps and sometimes it is 120fps. When the file is opened in QuickTime, it looks like a slow-mo movie from an iPhone.
The file in the ScreenGrab is large(28gig) that would take a few days as I’m also doing a 1TB upload to my DropBox. I’m sending a smaller file (to the DropBox Link) that I also tried and had a is,ilar result (output file was 60fps instead of 24fps.) I think both are likely to be variable rate fps as they report a slightly different “overall” frame rate in the QT info pane.
I recently tried to go back a few versions to see if I could find when the issue may have appeared, but I went back to 3.1 and it still did the same behavior of exporting many more frames than the original. So my initial impression that this is a new behavior is incorrect. I tried several other source files with constant (standard frame rates) and they work correctly. So It seems that variable frame rate files (which show a non-standard overall frame rate in the original source) are causing the AI to be not so"I".