I found some usefull comments on the youtube-link. Thanks for posting it.
" Here's a tip for the Amiga version for everyone who sucked as bad at jousting than I:
While "assuming positions", move the mouse cursor in front of the horses head (bottom left corner) and just leave it there... you'll get a whole new appreciation for tournaments."
"I figured? out the best way to win was to aim the lance at the bottom of the opponent's shield... But even that took practice..."
"jousting... i got it right after 15 years! u had to point at the white "X" on the horseman's shield... and? when very close, move the mouse upwards!
my life changed after that!
"