I'm not the expert but, for those of you running reflex sights on a 45 degree mount it should look like this. YouTube - Brownells - Jerry Miculek Practical Rifle DVD Segment, Speed Reloading Tandem Magazines, D2S5s2

YouTube - Brownells Presents Jerry Miculek Practical Rifle Trailer

Those are some good videos. I noticed he mounts the sight on the right side and tilts the gun in to use it. Is there an advantage to that side (as opposed to mounting it on the left) or is it more of a preference thing?

Yes it's faster and you move less to acquire the other sight. You move only your right wrist as opposed to moving either your head down to a second sight or adjusting the weapon higher, using both hands, to acquire a sight picture.

With my DDAB on the left side of my Mark III (45 degree) I won't have to move at all, just change eyes... Left eye for red dot, right eye for scope.

This is my setup. Luckily i had to raise the scope and set it back from the charging handle i guess due to my size as i couldnt use the scope in the recommended spot and lower mounts.
Anyhow it allowed me to get my TRS-25 on the top rail with my 45 degree mount.
For me on the right works best as you just turn the gun a bit and your head doesn't move nor do you loose cheek weld. I tried the left side and i had a tendency to pull my cheek loose to use both eyes. But not only that on the left it blocked my horizontal adjustments screw and i couldn't use it.

I wouldn't say there is a right or wrong side, It just depends on the person using it and how they use it. As long as your cheek stays planted it shouldn't matter. The only mounting system i don't agree with or like is the ones where they mount a red dot over or on the side of a scope, That just causes more issues than it helps. Both in repeatability and in trajectory.

Which is great if you don't use both eyes open while firing.

Kind of hard to do when your magnification starts at 3X.

I use my right eye at 3x and my left at 1x simultaneously and mentally calculate the earth's rotation and shoot flies at 200 yards in flight.
With Remington Golden bullets!

OMG. That's what I was doing wrong. Can I see the math on that?

Ummm, No. Its top secret at this time.