Replying to Computer/Video help please!

so im trying to help this old guy i know get his old Hi8 tapes onto his computer, which is an old powerbook g4 with OS 10.3.9. im constantly having problems using or even watching the videos, and after trying a lot of things (resetting ram, making sure it wasnt the videos that were messed up, repairing the disc etc) im starting to wonder, is the computer just too slow to be dealing with so much video? or is there some other problem?

im going to update his OS right now but any other input or advice would be much appreciated. thanks