How can I successfully export video from iMovie to a video hosting service? I've tried several times to export an iMovie project to Vimeo using iMovie '11 v9.0.9 updated May 2013. The video takes several hours to render, but fails at the end when it would follow that the video is to start uploading.

This is the error message that shows when it fails:


Unable to prepare project for publishing. The project could not be prepared for publishing because an error occurred. (OpWrErr: file already open with write permission)


What can I do to make thus work successfully?
This is error -49, OpWrErr: file already open with write permission.

Turns out, this is related to Time Machine running at some point while the video is rendering. 

It's possible to address this in one of two ways:


Disable MobileBackups.
Disable Time Machine entirely.


I chose the latter of the two and the export succeeded fully.