How to view videos in iCloud published iPhoto Journal using web browser?

If I publish an iPhoto Journal containing videos to iCloud and then attempt to view the journal from a web browser e.g. Safari, I see a single image corresponding to each video, but when I select one of them, I get a backwards, play/pause and forwards buttons, but those only control treating the images as a slideshow. I don't see any buttons that correspond to playing the contents of each video. Do I have the incorrect format for the videos (they are .mp4 files created using Handbrake from the original .MOV files which is what my camera creates)?

Here's the URL of the published iPhoto Journal.

https://www.icloud.com/journal/#3;CAEQARoQ8C9bYMtZRt9Fb0aFEnLakA;2335CFCE-383F-4 EB5-B99C-26054C3A4E97

Thanks in advance for any advice.

David