I cant view the vid - my connection playing up lately...
Maybe the pinions you have are not actually mod1 pinions?? I was sent some .8mod pinions that were sounding just like what you are describing...
Either that, or you have the mesh set too close or far apart... the pinions/spur gears should be smooth when rolling... Maybe order a pinion from the rc-monster store? i know it's another cost - but you will always use them =)

I noticed you mention it before, but it's probably not a good idea to rev with the wheels off the ground... You are better off pushing the truck along the ground to test the mesh if that's what you are trying to achieve =)

I like your servo plate brace btw... if i have any problems, i'll be adding one for sure =)