Serpent like UFO spotted over Mexico, but is it extraterrestrial?

YouTube is littered with videos claiming to show UFOs of some sort or another (my most recent search for the term UFO returned 30,000 results), but by and large, most show a single dot in the sky with no frame of reference that may be debunkable, but would never be provable as a UFO. Others that appear to be of some sort of UFO are actually, after closer inspection, something quite identifiable. Normally, I just ignore clips like this by and only post videos that defy explanation (or at least leave me wondering what I saw). My first inclination when I saw this video from Mexico was to pass on posting it, but then I thought it may be fun to put it up, explain what I think we are seeing and open up the comments for you to post your own theories about the video.

Here is the video in question (the UFO footage starts about 36 seconds in):

I believe what we are seeing in this footage is a balloon arch that has either been released or has broke free from its tether. At approximately 1 minute 15 seconds into the video you can start to make out the shape of the individual balloons making up the arch. If this is a balloon arch, a single balloon breaking free even explains the “UFO Orb” pointed out 2 minutes and 48 seconds into the video. What do you think the object in this video is?

Stunning UFO Snake Mexico 2009