I actually didn't know this bit myself:
**VERY IMPORTANT: **The Video Preload actor only works when the Movie Player that will play the movie has these settings:
The ‘position’ is 0
The ‘play start’ is 0
The ‘play length’ is 100
The speed is 1
So I have learnt something myself this morning. EVERYONE should read the article for sure!
There were four separate clips on the disk So -- while the image was the same -- there were four streams of video playing from four separate files. Performance wise, using four different clips should give the same results.