There are a few YouTube videos that I keep on returning to over and over again. For example, there's the Cowboys Herding Cats video, the This Too Shall Pass Rube Goldberg Machine video, and my “feel good” Where the Hell is Matt? Video.

If I really want to get my blood pumping, then a good standby is Grinding the Crack with Jeb Corliss. This was the first time I'd seen anyone doing what's called “proximity flying” in a wingsuit and it made the hairs stand up on the back of my neck.

Since that time, I've run across some other really amazing videos in the same ilk (I also love the music and singing that accompanies these videos). For example, this video of Jeb Corliss and Luigi Cani flying next to an amazing natural structure called Balls Pyramid is simply incredible.

More recently, I discovered this video of Jeb Corliss flying through Tianmen Cave, which is a natural hole in Tianmen Mountain in northwestern Hunan Province, China. This case is 100 feet (30 meters) wide and 431 feet (131.5 meters) tall, but when you look at it from Jeb's perspective as he flies towards it at around 150 miles per hour it looks like a tiny crack.

I tell you, my heart was in my mouth towards the end of the above video. When I saw it, I thought to myself: “Good grief! That's going to be a hard one to beat.” Well, it's been beaten because I just saw this video of Alexander Polli flying through a much smaller hole in Roca Foradada Mountain in Montserrat, Spain.

“OMG,” is all I can say. One of the commenters to this video said: “What I don't get is how he fit his balls through that opening…” I have to second the motion.