I found this at the MK Wikia, but I don't remember ever seeing this during the Soul Tombs level, or any other part of the game. where is this video showing Shang Tsung regaining his youth? thanks!

-"Shaolin Monks shows in a FMV in the Soul Tombs Shang Tsung restores his own youth with a combination of fresh souls and powerful magic, however in Mortal Kombat 2 Shang Tsung's bio and the MK 2 comic state that Shao Kahn restores Shang Tsung's youth and strength."