I saw this yesterday.  I was thinking yeah yeah, more balloons until the end where all the things spread out in a straight line.  That's really the only interesting part.  I'm not sure it wasn't still just balloons, but it would be hard to get them to do that.  I can think of one way that might work and wouldn't be too terribly difficult to prepare.  If you had a bunch of small ballons all tied together in line, and then tape all the balloons together into a more or less ball shape, and then sent them up like that, it might do it.  Once one of the balloons came loose, a strong wind could catch it and pull off another and another from the mass.  With each new balloon that came loose there would be more surface area and it would come apart faster and faster.  Since they're all tied together in a line, a stiff wind might blow them out straight like that.  Would something like this actually look like that once released?  I don't know, but it's at least plausible, and seems as likely as an alien starship anyway.

I like the video.  

I agree there is probably a rational explanation, but I don't know what it is.  My first thought was skydivers, but the motion didn't seem right.  Same with the balloon idea.  But who knows?  

Hopefully another video will surface with a better view that can be used as a cross reference.