A BVH file is a format that was developed by Biovision, a motion capture services company, as a way to provide motion capture data and skeleton hierarchy information in addition to the motion data. A .bvh file is nothing more than a text file that has data that was captured from a moving skeletal system. Another name for this type of data capture is “Motion Capture” which has been abbreviated as mocap. You can find tons of free BVH motion data on the web or motion libraries for sale in BVH format. By using BVH Importer you can convert all these available resources to something that After Effects can handle and enrich your motion content.
For more info: http://aescripts.com/bvh-importer/