I have a couple disagreements with each video. In the first one, why did he bother leveling the rifle along its length? If your base has cant built in you may go crazy trying get the scoped parallel with the rifle. I wouldn't know, because I haven't waisted my time finding out. Also, scope turret caps are known for not being perfectly square to the reticle. In the second video, no mention of sliding the base and or rings forward in the picatiny slot for the cross bolt. Also, although I have read good things about using playing cards to level the reticle off the bottom of the scope I wouldn't trust cards balanced on a picatiny rail to do it. Not to mention tightening down the scope rings with an object squeezed in between the rail and the scope.. And last but not least, the reticle doesn't have to be perfectly perpendicular to the bore so don't worry about getting it perfect. I prefer a couple degrees (haven't measured it) of clockwise cant because it is more ergonomic and comfortable behind the rifle. The only crucial consideration is that the reticle is parallel to the world when firing the rifle.