Didn't get to the bottom of how this video got corrupted, so I uploaded it again.
Here's a link to the latest version:
https://youtu.be/iRI4SnBFcc0

Thanks for bringing this to my attention Don. Well it certainly wasn't like that when I uploaded it. I just played through my original and it runs from begining to end with no problem and it's only 01:01:42 long.
My first guess is that my youtube account has been hacked and that somebody has edited my video. My second guess is that it's been corrupted by youtube. At this stage I don't know which.
I shall try and investigate.

When I look at the YT video, it's 1 hour 27 minutes long and most of it is a loop of the opening part with the lady in the green T shirt giving a briefing?

The video shows the Rhondda area off beautifully on what was the perfect spring day! Thank-you John.

Here is my Youtube video from the event
https://youtu.be/yn4eP4fibhI

Roller coaster indeed

Here are my photos from Saturday's event
https://www.flickr.com/photos/john_pp/albums/72157666933705467