Replied by Tony Murray on topic Re: Youtube videos not playing with API method
Ok, now I get it.
I've been copying the embed code into the youtube box. I should enter the code
www.youtube.com/watch?v=
and the 11 character youtube video code?
Now the video works as it should and the thumb box is auto filled too.
This has resolved all but my question on customizing the css (which is on another thread).