When I access the Plex Forums Release Announcements, not all content is encrypted

When I access this forum in Firefox 57 on Windows 10, I get a warning that part of this page is Not Secured, i.e. using http:// instead of https://

https://forums.plex.tv/categories/release-announcements

Looking at the page source, there are eight matches for http:// instead of https://

Can these eight links be replaced with https links?