Had this happen before by a Hunter AI in L4D2. We were on the first level of the first campaign. We were walking on the edge of the building and from out of nowhere, a Hunter leaps out of the window in front of us and over the edge - down to its doom. Funny, indeed it was. XD
parkour is where you use motion and agility to cross, climb, jump, etc. everyday objects such as railings, fences, tables, etc. with efficiency. the point of parkour is to condition your body to adapt to any terrain and find alternate, shorter, and more efficiant paths of travel. alot of people make videos of their "parkour grounds" in which they practice. it's a good way to stay in shape and practice your skills.