Finally sorted it out for streaming using Cloudfront but it needs some clear instruction or specific set up fields in the JW7 plugin
By entering the rtmp as follows rtmp://xxxxxxxxxxxxxxx.cloudfront.net/cfx/st/S3bucketname/mp4:filename.mp4
the player will play.
xxxxxxxxxxxxxxx.cloudfront.net = your Cloudfront URL
S3bucketname is the name of your bucket in Amzon S3 relative to the Cloudfront rtmp setup
filename.mp4 is of course the name of the file in your bucket.
Another tip – the JW7 plugin puts the player on the left of the page by default. I wanted it centered so I used
<div style="”margin-left:" auto; margin-right: width: 650px;”>[jw7-video n=”1″]</div> in the Text window.
The 650px needs to be changed for your specific page setup. Increase it to move left, decrease to move right.
Trial and error will get you there.