I bought a K-7 from a forum member a few months ago and was having problems with a clicking or thumping sound every time I tried to shoot video. It is quite loud and at a regular rhythm, probably about 4 clicks a second or so. I turned off the shake reduction in the movie menu but still had the noise. I just went in today to give it another try and in the movie menu I set the movie aperture control to "fixed" from "auto". Noise is gone! I'm using an old 50mm f1.7 manual lens and I guess the sound was the camera trying to control the aperture.
I thought I would share since I couldn't find a thread when I was having the problem. I hope it helps someone else.