"I don't think you say what the baffles are made of, how big they are, or how you sew them onto the main body (fold over the edge and sew through two layers of baffle material?).
The picture of the baffles is difficult to comprehend because the baffle is the same material as the main fabric (answers my first question)."
If you look carefully at his directions, you'll see that he uses sewn through baffles. This means that the top and bottom are sewn together to form the baffles, with the resulting seam forming the baffle rather than using any sort of additional baffle material.
This has the advantage of saving weight and is much easier to sew than regular baffles, but it isn't as warm and has the potential issue of creating cold spots. This means that any sewn-through quilt is probably, like this one, going to end up being a summer quilt.
Of course, if you plan it that way from the beginning, this isn't a problem at all and leads to having a really nice, really light quilt for warmer weather use.