The clip is comical to me because of the various dramatic traits it contains. One of these traits is dramatic irony. The clip shows irony because the audience knows that Dekker will fail the impossible feats at his age, but it is still hilarious to watch him attempt them. Dekker also shows a great amount oh hubris, or arrogance, in the clip. This causes hamartia because he believes the military wants his special skill set but this judgement is 'off the mark' because they are just asking for a recommendation. The clip also has peripeteia where Dekkers fortunes turn from good to bad. I believe this starts when his misses his first attempt of blocking a speeding bullet and having it find it's mark and lodge itself in Dekker's left shoulder.
There are lessons to be learned from this clip. One is that it is rarely good to have false confidence in your abilities, the other, of course, is to never come out of retirement.