(easy first steps)
1. Precompose your clips and order them according to your song.
2. Add a camera layer and null object layer over your clips.
3. Set the null object layer to 3D, then proceed to parent the camera layer to the null object. (not sure if the order matters but just in case; put the null object layer under the camera layer as seen on the video)
4.Set your clips (layers) to 3D.
5. Set (untouched) keyframes on the first clip, then go to the second clip and do whichever transition you wish.
6. Copy and paste the transition onto the clip below. (that's how in the video it seems to go back to normal. Note: he only pasted the transition, he didn't reset anything).
7. Freeze both your clips on the last frame.
8. Add motion tile.
9. Do a fade out transition in your first. (no clue how he could do it under the second clip and still get a good fade out, so what I did was put the first clip on top of the second one and played around until I got something "smooth")
10. Select your keyframes and easy ease them.
11. Go to graph and and do your magic. Just as he said, there's really no special trick to it you just have to experiment around and find the results you're happy with.
12. Repeat process on the rest of the composition and don't leave the graph on a flat line, try to keep it moving so you get a smooth finish.
13. Add the final touches with black bars, RSMB, and motion blur.