The above link has instructions about setting up the Beagle Board Codec Engine.
Codec Engine is necessary in order to make use of onboard TI TMS320C64x+ DSP, which is a DSP on the Beagle Board.
This enables an user to make use of beagle board's DSP in order to decode video and audio.
Using DSP to decode video help to meet real-time playback of a video stream.
The above link also has instructions regarding running some sample applications provided with the files.
It also has instructions about building your own DSP Link file.