For the record, I think the confusion here was that “MP4” is being used for a couple of different things. MPEG-4 Part 14 (aka MP4) is a container format. MPEG-4 Part 2 (aka MPEG-4 Visual) is a video codec with a number of profiles including Advanced Simple Profile (pretty stupid name for a profile, BTW
). MPEG-4 Part 10 (aka h.264, AVC) is a different video codec.
For Twitter video uploads, we expect an MP4 container with h.264 video and AAC audio. We do not currently support the MPEG-4 Visual codec for tweet_video uploads.
Thanks!
Josh