I’m here to save the day. The root of the issue is that itunesconnect does not like the format of the file saved by quicktime, or pretty much any format for that matter.
I was able to find just 1 file format that worked. You will need a free program called HandBrake
Use this program to convert the file you are trying to upload with the options I have highlighted in this screenshot:
(Optional) If your video has no sound, go to the audio tab in HandBrake and remove the track, like so:
Note, when you are doing multiple conversions in a row, sometimes the output size gets screwed up, keep an eye on that (it might be a bug in handbrake).
That’s it! Upload the file created by HandBrake and it works! Consider donating to the developer of HandBrake for an awesome app.
Edit: Quote from comments:
For those who are struggling (like I was) to make a video 1080p
(1920×1080), don’t forget to go to the Picture tab and: change the
Anamorphic setting to “Off”, change the Modulus setting to “8” and
last but not least change the Cropping setting to “Custom” and set the
Top, Bottom, Right, Left to “0” – gaskbr Aug 18
Edit 2: You have to set the audio right also, looks like Apple don’t accept files without audio channels anymore. Set the codec to AAC, 44.1 (or 48 kHz), bitrate 256.