It should work. Have you got all of the diamonds/keys? On the second screen, there is another screen to the right that people miss. You need to jump off the tree branch. It's a tough one, you have to take a leap of faith! The YouTube video was of a version which contained a bug, which meant you could complete the level without finding all of the diamonds.
Viewing post in Get More Diamonds (VIC20) comments
You both make good points. In our defence, it's the only screen in the entire level where you would possibly need to jump to access the next screen, so it's really the only choice remaining and the only one that would risk a life. It was to encourage exploration and risk taking. We have included a map pack so hopefully you can still enjoy the game. If not, thanks for the feedback and for trying our game. Hopefully our next game is more to your liking :-)