This article describes information regarding video output on the beagleboard.
The current framebuffer diver has a generic interface (/dev/fb) but also a specific OMAP (2 and 3) interface for YUV overlays (/dev/fb1).
In order to use the YUV overlays (/dev/fb1) you need to specify some kernel parameters:
For this particular case you'll need a corresponding consistent DMA size configuration:
In order for the display controller to work you'll need a patch from Mans Rullgard which can be found here. (At least at the time of this writing it's still needed 2.6.27-omap1)
For examples of how to use the custom omapfb see: