After rendering as MOV, file won't play in Quicktime.

Don't lol but my MOV file didn't move either when I opened it. Solution > View > half screen displays the Run button that I clicked to move the MOV file.

Todd this was not the correct answer and you really need to stop your campaign against Apple. It's looking like a tantrum now. It also does not help the widely perceived view by mac users on here that you have a chip on your shoulder when it comes to Apple issues.

It was a operational error by the user. The displacement was so subtle and spread over too long a time that the movement was not clear. Once you dragged the keyframes together over 3 seconds the movement is then obvious. This took me 10 seconds to work out and no conspiracy theory or toys thrown out my pram was needed.

As for your statement on Apple removing codecs, there is a counter argument which I'm sure Apple would make... You now don't need to keep installing various codecs, of which some caused system errors. You can now open any codec and yes wait for it to be converted... But it leads to a better user experience for the consumer market. If like me you want professional control you can install Quicktime 7, use Apple prores or Compressor.

That is the more subtle and correct answer!

Thanks for the reply, however, I don't know what to do with these files then? I am exporting them from After Effects. In the past, they have been relatively small video files and Quicktime has been able to convert them.  But these ones won't even play on a program like VLC either. If I open them in VLC they don't play smoothly, they're choppy, playing maybe half a second at 10 second intervals. I've never experienced this before.