The intro function from the editor does not work in MP, unfortunately. You have to make a separate camera script that films actions and events on the actual mission map to make it work. Then you can start this camerascript like any other script directly in the beginning of the mission. I suggest you start your intro in the toip line of your init: [] exec intro.sqs (or whatever you named your intro)
The pbo-tool does exactly the same as the export function. I also prefer to use that one.