iOS app preview video not saving in iTunes Connect

I experienced this problem too and ended up by using free app called HandBrake to re-encode my mp4 video with specs described in the developer.apple.com

Basically I just changed these settings :

• Video Codec (FPS) to : H.264(x264)
• Video Framerate (FPS) to : 30
• Audio Codec to : AAC (Core Audio)
• Audio Mixdown to : Stereo
• Audio Sample rate to : 44.1
• Audio Bitrate to : 256

UPDATED 10/09/2020: The help link provided in this answer is from the old developer website which now forwards to the home page of the current developer help website. The current link with this information is in the link below:

https://help.apple.com/app-store-connect/#/dev4e413fcb8

We ended up having this problem as well and couldn't for the life of us come up with a file that would work.

As it turns out, the video was fine all along, but iTunes Connect has a very short upload time window. Uploading a 39MB file on an ADSL connection with 800kbit/s upload is apparently not good enough. (it didn't even work with a shorter, lower-quality 13MB file) It all worked fine first try via the iPhone's 3G personal hotspot with a 4Mbit/s upload speed.

Of course, that's not what the error message says. Sigh.

convert your videos online using this site http://video.online-convert.com/convert-to-mp4

and set the following

vid bitrate : 10240

frame rate: 30

audio quality: 256