It was some MIT students before, now, a father and son team, from Brooklyn. Much more impressive since they use HD video camera.
I would think keeping the electronics from cooling is very important, which is why the camera or GPS system could easily die when their batteries get too cold, like what usually happens to me during my star-gazing night.
I wonder, since its descent was due to exploded expanding balloon as air pressure decreases (And not the fact that super light gas running out through balloon skin as I was once told by a "Doctor"), and I'm more convinced this is the reason helium balloons don't go on for ever, what if one were to include some partially gassed balloons, so that the rise is maintained to some extend.