This is from Main Concept's Support (quoted with their permission):


Some clarifications regarding smart rendering...
When the MPEG Pro plugin is installed, one should use also the MPEG Pro project presets for HDV and other formats, not the ones from Adobe.

The reason is as follows:
In Premiere there are so called Editing modes. An Editing Mode consists of an Import, Player and render module. These three communicate with each other to figure out whether smart rendering is possible or whether material on the timeline needs to be rendered. When MPEG Pro is installed all mpeg import is taken over by its import module. But it can not communicate with the modules of a Premiere project types editing mode. There is no standard way for this.

If the user has an already existing Adobe HDV Project that he wants to finish he should uninstall the plugin temporary. But then he will not have the MPEG Pro export capabilities available. If he needs them there is an other workaround. He can rename the module importerMCMPEG.prm in the plugin path, which is something like C:\Program Files\Adobe\Adobe Premiere Pro CS3\Plug-ins\en_US\MainConcept. Then the Adobe mpeg importer will handle the mpeg files again.

For future projects he shall use MPEG Pro project presets only. Only he will have the full benefit of smart rendering.

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