CooL... didn't know they existed. I've used a mandolin capo on my uke.. it works well. However usually I don't employ a capo. It makes me learn more chords... hee hee..
I will upload a YouTube video of it as soon as it arrives so just follow me YouTube the link is below. I've recently lowered the key of my uke to a baritone from a tenor and have a wedding Saturday and no time to work out the key changes hence the volcapo
That's definitely an interesting design for having that adjustable tension. I'm not sure how practical it is, but the concept is pretty cool, and it is definitely an attention getter.