Are you talking about testing after publishing and uploading to Moodle?
The error message is because you have an HTTP link to the Adobe website somewhere in the project's code (probably in the index.html file) but it needs to be an HTTPS (secure) link instead because you are playing YouTube content in an iFrame. The YouTube link is HTTPS and it's not happy about being called into a page that has insecure HTTP links.
There is probably no Flash object in your project since it's now entirely HTML5. But the link to the Adobe website is to the page where you would previously have been able to download the Flash player. That's what the error message is saying.
So you need to locate that link to the Adobe website and remove it, or else change it to be HTTPS and not point to the Flash Player download page. Ideally these changes should be made in the HTML template file in the Captivate install directory so that it doesn't keep getting inserted each time you publish.