Okay, let me try and "imitate" what's happening there. First, a clunk from the mirror. Then, almost instantaneously, the sound of shutter inside that you probably won't hear since the first clunk covers it up (you can try dismounting the lens and pushing the mirror up - you'll see what's called shutter curtains (they cover sensor). Then, after exposure is done (and all the whirring from SR), you'll hear the sound of the shutter closing (I don't know how to describe it... but it's kind of like something sliding inside?), and almost immediately afterwards, the clunk of mirror bouncing back in position (in SLR, mirror is between lens and sensor and reflects the image up from its original path; to make a shot, the mirror has to go up so that it doesn't block the way to the light; after the shot is done, mirror has to go back to its original position - it's real easy to see for yourself, just fire without a lens and look inside the camera
).
There are also some other sounds - I think I heard sometimes the sounds of springs inside, as well as the aperture lever's sound... K10D and K20D aren't that quiet