I have Jaap's video, or at least did until I loaned it out... I'll have to check to see if it made it back or not.
For constructing the traditional long yumi I don't think I'd want to try it any other way than with the wedge method. He says he's made glass bows like that as well.
If I remember right, the core of these bows is traditionally very complex, consisting of 3-5 vertically laminated bamboo slats with hardwood edging (mulberry I think). The core was then tapered and faced and backed with raw boo slats. Pretty cool stuff. There are lots of Kyudo sites on the web with more info.