Multimedia macro with a video doesn't work for portal only user from the portal in a KB article

Summary

If a KB article contains a video file, this will play fine in Confluence, but will not play back through the portal view of the customer.
Note: it works fine as the user is an Atlassian Account user, it doesn't if the user is a portal only user.

Steps to Reproduce

1. Create a page in a Confluence space that is linked as a KB
2. Add a short video to the page using the Multimedia Macro
3. View the article from the portal as a portal only user

Expected Results

Video should play fine in both Confluence and Jira SD

Actual Results

It works from Confluence, doesn't start/work from the JSD portal

Notes

The tests were made using an mp4 format video.

Workaround

Embed the video as an attachment macro in the page content, the portal only users are then able to download the video.