Do you remember F.N.G., the training course in Call of Duty 4: Modern Warfare? The one at the beginning of the game where the SAS guys have you run through a training course to suggest what the game’s difficulty should be set at? It would seem that, before the course and after the segment where you slice open a watermelon with your knife, there were two other tutorial lessons that Infinity Ward decided to cut from the game’s final release.
A Japanese modder going by the name Qrysalis happened upon this remnant data while examining the PC version of the game, and decided to create a small mod that would make it accessible. You can see the results above: after the aforementioned melon cutting there is a sequence that goes over grenade throwing and C4 use, and then a quick obstacle course that shows how to move around obstacles by jumping, crouching, and crawling.
If, after watching the above video, you really feel the need to try this out for yourself, a link to download the mod can be found on the Infinity Ward forums.