The cutscene will play and fade into the last race result screen.
I illegitimately jump to the final boss and defeat it.
This run only plays through the 4 levels that are available on the easy difficulty (Cub). The other 5 levels are only available on harder difficulties (Prince and King). Even though beating the Cub mode does give the credits, all the viewers agree that this 9-level game doesn't feel completed if one just reduces the challenge to make things easiest, and only beats less than a half of the game. This is the case when the easier difficulty setting isn't justified, so for any future submission of this game some other difficulty should be picked, to show the entire game. Judging by the FAQ though, King difficulty only reduces your health and increases enemies' health, so Prince mode would be enough here. Rejecting for the flawed goal choice.
There are three different maze layouts possible for each of the three stages. To get each most optimal layout, I wait a few frames before slaying the final enemy of each previous stage.
By default HL1 is limited to 100 FPS. It's not vsynced, so depending on the computer performance the FPS can go below, down to 0 (effectively 4 as FPS below 4 is treated as 4 by the game and isn't useful). The movement is generally faster the higher the FPS, so 100 FPS is optimal for the movement.
