06/07/2016 (Tue) 00:50:34
an update on this. StephenLynx says we either have to stop allowing large files or turn-off animated thumbnails.
What's happening is that the number of frames in the animation/video is taking too long for our server to process before the AJAX and node processes timeout. And then post can't continue posting normally unless it has a thumbnail. So instead it strips the fiile and makes the post.
I'm going to look into other solutions on our fork. Including using a temporary placeholder thumbnail, that will be replaced if the processing does finish.