Hey freeonthree ,
By the looks in your video the prop you are using is a Master Airscrew classic. Is this right? I used to use Master airscrew wooden, Zinger, Topflite, and APC. Since I gone with gassers, one day I sprung for a good quality prop. It is like night and day. I couldn't beleive a prop in the same size and pitch could be that much better, but they are. I know they are more money, but you should spring for one and give it a try. I found Vess is the best, followed closely by Xoar and JFX. I see lots of props on E-Bay( MA, Zinger, TF, etc ) but I don't even bother. It 's like putting skinny little tires on a dragster. You never get the power of what the motor can do. I got my Xoars at http://bobshobbycenter.com/ the 18 X 8 that you want is $17.45. A Top Flite 18 X 8 @ Tower Hobbies is $14.00. For an extra $3.50 try one, I think you'll really like it.