Аll actions shown in the video

-Select infinite ammo (You will still get the achievement). Just press custom game in the menu, where you have to select the difficulty.

-If you die, don't load any savegames, even not the one which was created right from the beginning. Quit the game and restart it manually.

-Turn the auto-aiming with notation in the menues on.

-For the first rocket jump, you need more than 50 healtpoints and 50 armorpoints..