I did not see anything but color grading. This has nothing to do with the Alpha channel. Saturation is pulled way out, blacks are crushed. There are a bunch of standard tools that come with AE that can be used or combined to create this look. Some of the shots had all of the color removed, some left a little saturation and pushed everything to reds.
Are you new to AE or PPro? If so, read up on the Color Correction in the help files. Do a web search for Color Grading or color grading.
I'm not new....i've been a while
Just wanted to know some stuff
This is pretty basic color grading stuff. If you have plug-ins like Magic Bullet or Colorista it's quite easy to achieve this look. Speed Grade, which comes with the Adobe Suite is also very good. Read up on color grading and practice. It's not magic and there is not single click solution for every shot, but it is possible for most folks with good color vision to learn how to do color grading if they know color theory.
Start here to learn about color grading and color correction in After Effects/