Old tutorial is ooooooold.
Are you using iMovie 08 or 06? I have to investigate further on 06, but on 08 many codecs are no go. I found that h264 at 100% quality in an mp4 container works just fine. Are you on an intel or PPC? Because you should no longer use that tutorial's methodology. It is not longer accurate. Rather, read the stickies at the top of this forum.