I'll summarize for those who don't want to actually watch the entire 17 1/2 minute video (the last six minutes of which consist of a Piano Rendition with the word "LEAP (R)" on the screen)
A keyboard with two keys dedicated to CMD-F, CMD-Shift-G .
Wow. Talk about over-engineering. This was a software problem, not a hardware problem, solved about ten years prior to 1987 by vi:
/ search string
? search string
n to repeat
No thumbs needed.
The idea is very similar to Firefox's incremental search (and for that matter, even more similar to Emacs C-s and C-r).