Broken video example in Reflow understanding

[patrickhlauke]

The embedded video in https://www.w3.org/WAI/WCAG22/Understanding/reflow.html#examples fails because it points to an external site (@alastc 's) where the https certificate fails at this moment.

Suggest moving the video itself to the repo itself, and serving it directly from w3c (like we do for images)

[alastc]

It would be great if @kfranqueiro or @iadawn could create a place for us to host larger files so they don't end up in the repo.

[patrickhlauke]

Closing this issue itself, as the video isn't broken anymore. However, leaving the PR this spawned #3993 open for further investigation.