You have to ensure you keep the quality of the video. By default dolhpin will significantly reduce the quality to reduce file size. Go keep the HD quality go to Admin>Modules>FlashApps. Click on Video Player>settings. Set Record FPS to 25, quality to 75-100% (test out what you think will work, I keep HD in 75% to help a little with file size). Click the box that says "Save video orgional quality while converting. This is the setting that will keep HD movies HD, otherwise you reduce the quality.
If you set 100% record quality with the Save origional quality, you will have a virtual clone of the movie (too bad we can't have 30fps for max quality but eh).