You technically CAN do this if you scrape the non-SSL page and serve a cached version from your own server with all the resource URLs tunneled also. However, this will almost certainly violate the implied contract your SSL certificate provides, basically by displaying content that is not known to be trusted and passing it on to the user without letting them know it is not trusted (has no SSL cert). It would probably also violate any copyrights on the original content.
I'm sure you can also get around the SSL warning if you load the content inside a Flash container, unless Adobe/browser makers have now closed that "workaround". But again this would be breaking your SSL contracts by displaying untrusted content and trying to mask that from the user.