I investigated and found the video had music in the background. The video was made from a dashcam video and the car radio had been playing. Didn't even notice there was music in the background.
Deleted the video and edited the video to remove the sound. I didn't know how to do this so I checked the internet. There were many suggestions such as using other products, but I couldn't help feeling the Windows 10 Photos app should be able to do something I'd consider fairly basic.
I found a few options relating to sounds, but then I right clicked on the video and found a Volume option. On the video itself is a speaker, so I decided to click on the speaker. It turned out I could mute the sound which I did and saved the video. Excellent. The sound and thus the music was gone. Just what I wanted.
The video can be seen at https://youtu.be/ZYNhIRB4giU
I hope this tip helps others.
Kelvin Eldridge
www.OnlineConnections.com.au
IT support.