It has been over 40 years so apologies if there are errors. I think it was during the 1980 tournament when UL played St. Johns. Griffith was on the right side of the lane and crossed the lane toward the goal, and as he passed the rim, he leaped up, caught a pass, and dunked the ball over his head without looking at the goal. Since then, we've seen similar dunks, but at the time it was met with "What did I just see?" kinds of reactions.
It's buried in this collection. Lots of talking heads to skip through.