This demonstrates how to install OpenSceneGraph. This version is intended for users already familiar with Mac OS X. (1:04)
This is a simple drag-and-drop install placing Frameworks in /Library/Frameworks and PlugIns in /Library/Application Support/OpenSceneGraph/PlugIns. These may of course be placed in the per-user directories, i.e. ~/Library/Frameworks and ~/Library/Application Support/OpenSceneGraph/PlugIns.
This file is hosted at OpenSceneGraph under the Mac OS X Tips section on the Wiki and is also mirrored on YouTube.