Well actually the result of my test is that you DON'T need it - at least in the water it hasn't been very helpful. Since surfers need their arms for paddling, putting the camera in one arm is not very recommendable. I constantly hit my board with the camera and was afraid of crashing it all the time, haha! The images provided don't add any value either, so the price of €55.00 for "The Strap" hasn't really been worth it.
It's surely a nice add-on for people who do sports outside the water, but it's not the best way to shoot a surfing session.
"Esta es muy hermosa" would mean: "This one is very beautiful."
So: thank you - muchas gracias :-)