A few comments after looking at this a few times:
I think what you have is a reasonably good low-speed ramjet. Like the original Maggie Muggs, the diffuser is not ideal, but probably OK. I think your only real problem is air supply. You're not really running her hard enough, at least in the video. You do get good, stable combustion, but I doubt that the net effect is much better than a thrustless burner. After startup, I would try moving the air supply MUCH closer to the intake; naturally, that will force you to use a LOT more fuel to maintain combustion.
When you have it right, the sound of the blower will be completely drowned out by the jet, because the internal pressure will be significant (a couple of pounds per square inch, at least). If you can get it to the point where the flame looks good and the noise starts to scare you, you've got it. Of course, I'm not sure that a weldless design can stay together for that! Again, it ought to look like Steve's video when it's really running well.