This is happening with me too - same thing.
Though I was unable to find any decent information online relating to this error, I figured out the problem.
Firstly, it seems that you are not permitted by CS5 IDE to assign vid.skin='http://remote/url'. You will always get that error if you load a valid skin. No idea why.
Secondly, the problem when running it in the browser is I was loading vid.skin from a domain different from the web page itself. To get that working I had to set up the Flash security.
1- Set up a crossdomain.xml file on the remote server
2- Specifically call Security.addDomain( 'remote.com', 'other.com', ... );
After taking these steps, the skin now displays correctly in the browser, even if it doesn't work well from within the IDE debugger. For the IDE debugger to work you have to hardcode the local file location of the skin, and expressly NOT call vid.skin = 'http://remote/url'
Thanks for that info!