Zartemus worded how a squeeze worked almost down to a tee. Quoted/Edited from Zartemus' comment:
"There are HIDDEN NOTES at the end of a fill, under the green note. Since the hitbox for notes are a tad large in RB, you can hit the green slightly early, snag the overdrive, and then hit the hidden notes for extra points (200 per note squeezed). It's treated at a 1/32 note."
EDIT: The text should read 205,150 to 205,750 before the Orange Crush squeeze demonstration. I wrote 204,150 to 204,750.