Setting a Poster Frame for iCloud Photo Sharing
The Question:
How do I set a custom poster frame for videos shared via iCloud Photo Sharing?
Use Case:
I have converted old VHS family movies into small 3-5 minute segments and want to share these clips to my family via iCloud Photo Sharing. This will allow the videos to travel with them on their iPhones.
The Problem:
These segments are stored in the Photos app. I have selected some of these segments and chosen a poster frame - this works. I right click, choose Share to iCloud Photo Sharing. The file appears in a newly shared album, but the poster frame is reverted to the first frame of video. In the case of VHS, this is a scrambled frame, or a frame that does not clearly display the contents (such as a couch, or the sky).
Right-clicking a shared video grays out the option for reselecting a poster frame.