We tried to reproduce the issue you have described on our side, but unfortunately wit a little success - on our test page everything works like a charm as it can be seen from the screenshot I've attached.
Please, prepare a small running project, that contains RadRotator, VE, your layout and CSS files, and then open a new support ticket and send us that project so we are able to help. Also, check if your page is in standards compliance mode, and exclude your styles, just for test - in order to view if the problem still persists.
In RadRotator we are not using vendor specific (-moz-) properties, but I believe that we will be able to help.
the Telerik team
Check out Telerik Trainer
, the state of the art learning tool for Telerik products.