Well, as 1 point, Link isn't Kokiri. The Kokiri were child-like forest elves from the Ocarina of time. They NEVER GROW OLD. Link does. Link is a Hylian, or a human with pointy ears evolved to "Hear the voice of the gods", after the human race was sent up to live in the skies whilst the Goddess Hylia united the other races of the world and ended the tide of monsters making it uninhabitable and all that. The Great Deku Tree explicitly tells link that he is not Kokiri, and says that his mother was fleeing war in the human realm, and entrusted her baby to the Great Deku Tree as she was dying. So, link is human - kind of. Human, but pointy ears.
HOWEVER, Link contains the Triforce of courage, especially in Ocarina of time. Zelda holds the Triforce of Wisdom, Ganondorf the Triforce of Power, and Link the Triforce of courage. This powers link up, as we see countless times during the series where a character initiates triforce power mode and gains stupid powers - like Ganondorf turning into his giant pig demon Ganon form.
Additionally, Link often receives blessings from fairies. One of these halves all damage. I'd say its therefore safe to assume that all these forces are halved, and Link is able to withstand more than the human body would even without the forces being halved.
As has been pointed out, the video author obviously doesn't actually know physics or mechanics beyond a highschool level. The number of mistakes in the video is ridiculous and has already been covered. As has the dodgy math of trying to figure out sizes from in-game assets in a game not scaled to be realistic, and with graphical limitations.
Beyond that, the video picked the example that would best prove its point, rather than the one that would best disprove it. The Longshot may be a stretch to see if it would work, but what about the normal hookshot? A LOT light, a LOT less force, and in all probability its where the calculations started, but it turned out the hookshot was 100% legit, even with the dodgy maths, and thus the long shot had to be resorted to instead.
Basically, would be a good highschool assignment to hand in, but if we're trying to look at this properly, the video fails to do so. Yeah, its for entertainment, but it entertains me pointing out all the flaws in it too =P