You can open a MotionBuilder FBX file by selecting File > Open File from the main menu bar.
When you open an FBX file in MotionBuilder, you can choose which contents from the file you want to load into MotionBuilder. For example, you can select whether or not to include scene elements such as models, cameras, shaders, as well as takes and so on.
To open an FBX scene file
The Open Options window appears with the following default settings for the incoming file:
The scene elements load into MotionBuilder.
For information about saving a scene file, see Saving scene elements, animation, settings, and takes.