I think it will be much easier for you to embed ActiveX instead of the Netscape plugin.
Here's a step by step guide how to embed a Flash movie into a dialog-based C++ MFC application.
That guide is for the old version of visual studio. In VS 2012, instead of the step "Project menu, select Add To Project sub-menu and then click Components and Controls" just open the dialog resource, right click on the dialog, "Insert ActiveX Control" then choose "Shockwave flash object". Then resume that guide from the step “Right-click on dialog and select "Class Wizard" to invoke Class Wizard”.
P.S. Begin with a simple SWFs from your HDD to debug your embedding code, only then experiment with your browser games..