Further investigation reveals the cloud service (video.internetvideoarchive.net 52.237.130.0) is not distributed internationally but only based in Chicago, US. This is causing lag due to high latency outside of the US. In my case from Australia south coast, 5-7 seconds before any pre-roll and/or trailer for movies start, making this feature useless.
Even though its a poor choice by the content provider, I’d say this is beyond the control of Plex so I don’t see this changing any time soon but would be happy to hear something from Plex support?