Yes, The Media SDK dispatcher is part of the static library linked with your application. This library allows the application to call the appropriate implementation, which resides in the Software DLL. Please see the section 4.3, including Figure 5, for more details information.
The Windows implementation of Media SDK utilize Microsofts graphics acceleration architecture and there is currently a dependency for a usable graphics device which has a requirement that a user be logged in. Microsoft and Intel have been working to allow session 0 usability in the future. (Youre usage model is desired by others as well). Please watch this forum for information about when this capability will be available.