That isn't buffering, that is clipping physics. It's still good though, that abe doesn't run into walls. Hehe, I love blind muds!
Buffers store information. It reads info off of a disc, puts it in the buffer and then gives it to the computer when it asks for it. If the buffer overflows, the game slows down and lags, and if it has less info than the computer wants or needs, then it has an underrun and crashes. This is when "viods" open up in the game and your character falls into nowhere, because the correct landscape detail was not loaded into the buffer before the level loaded.
The same thing happens with typing, writing CD's, viewing images and listening to audio.