Here's my vid.
Note theres 40 seconds of nothing at the end of the vid... not sure why. stuffed up some editing settings.
Any way I agree. Short line trainer kite is a no go. it doesn't work. You need the normal or near normal line lengths.
This is my longboard of choice. Its low wide and has the widest stickiest wheels on the planet! ye freaken ha. I can tell ypu that carving up concrete on the bad boy is sublime.
Now I have also used my landboard aswell on the concrete. The landboard is by far easier because you can hold more power and also blast off into the grass without face planting. But ultimately it is not as lush as carving concrete on a smooooooooth longboard hmmmmm.