OD MDD Preview is a custom object plugin that allows you to display a mdd file. This can be extremely beneficial when running into issues with a mdd to actually see whats inside of a mdd:

Options:

• Color: Defines Color of the Display Points
• Point Size: Size of the Points in the display
• Display ID: When enabled, the point id (which would be the same as the Objects Point IDs)
• MDD File: Specifies the to be loaded MDD File

Here's a how-to video showing OD MDD Preview in action.