This question already has an answer here:
I'm creating an app preview for an iOS app using Apple's instructions (record video using QuickTime, import into iMovie, File -> App Preview) yet I get the following error message when I attempt to upload the video:
"Your app video preview is in the wrong format. For more information, see the Developer Guide".
The video is Mpeg 4, 640x1136 etc. so this seems odd. Has anyone been able to upload a video in this way?