For longer clips, you may want to just play it directly from the DVD. Then, after you finish showing the clip, you’ll need to get back into PowerPoint to continue your presentation.
While it’s true that the media file is linked to the PowerPoint presentation, if you use one of the formats described below, it will still display on the PowerPoint slide – if you don’t use one of these formats, you can hyperlink to the file and play it outside of PowerPoint (in QuickTime Player, for example).