I Mary,
Thanks for the response.
We have been able to upload each presentation into its own folder in Moodle... then set the 'main file" as "story.html" (similar to "index.html" as you described. This works well if all presentations are stored on the Moodle server.
As my client wants to record two presentations per week including narration I was hoping to store and access (play) the presentation from outside Moodle. This strategy would reduce the course file size.
I believe now that I misunderstood the idea of "Repository". My understanding now is that files may be stored in a "repository" like Amazon S3 ; Dropbox etc. but still need to be uploaded into Moodle to run.
The URL link to Amazon S3 looks successful... just need to tidy up the security settings. I hope to limit access to users coming from our website.
Thanks all for your assistance.
Cheers
Mark