In 1989, Pantera guitarist Dimebag Darrell auditioned for an open guitar spot in Megadeth. He was accepted, but upon finding out that his brother Vinnie Paul couldn't come along, he declined the offer and instead focused on Pantera.
At this point in time, Slayer had already begun to carve out their legacy in heavy music, having already released Reign In Blood and South Of Heaven. Pantera were yet to find similar success, and were struggling to find themselves a record deal. The below video has two hours of footage, a lot of which shows Slayer guitarist Kerry King jamming with Pantera as they run through riffs from both bands' songs and even some Judas Priest tracks. Towards the end of the video, Kerry King even gets up onstage with Pantera to shred out four tracks. The list of timestamped songs can be found underneath the clip.
Here's everything that goes down, timestamped (thanks to Loudwire):
WITH KERRY KING:
Dimebag & Kerry King Jam @ 0:00
"South of Heaven" (Rehearsal) @ 10:57
"Raining Blood" (Rehearsal) @ 24:55
"Power Metal" (Rehearsal) @ 34:56
"Deathtrap" (Rehearsal) @ 44:30
"Green Manalishi" (Rehearsal) @ 48:43
"Metal Gods" (Rehearsal) @ 54:04
"Hell Bent for Leather" (Rehearsal) @ 58:03
BACKSTAGE: @ 1:05:54
Intro ("Shattered" demo) @ 1:07:56
"Over and Out" @ 1:09:13
"Psycho Holiday" @ 1:15:06
"Heresy" @ 1:21:12
"We'll Meet Again" @ 1:27:21
"Domination" @ 1:33:11
WITH KERRY KING:
"Raining Blood" @ 1:41:14
"South of Heaven" @ 1:43:42
"Power Metal" @ 1:47:56
"Metal Gods" @ 1:53:35
Listen to Pantera now.
