There's this one too. At 7:40 there's a flash of light, then the sound fades out.
I've seen several comments about it being the "HAARP" thing.
HAARP is a load of bull, it's just a freaking weather station or something like that. I don't know where the people are getting this whole "weather altering doomsday weapon" from.
HAARP is a scientific instrument that has the capability of heating, or resonating, certain layers of the ionosphere, ostensibly for purposes of investigating radio wave propagation, etc. It has it's own official website, and is operated by physicists from prominent universities.
If the video posted by R1600Turbo is valid, then the phenomenon in question obviously has an atmospheric aspect to it, and it is related to lightning. Typical thunder comes from the cloud-to-ground lightning discharge channel. It may be that the thunder we heard in the video was due to a form of intra-cloud or inter-cloud lightning discharges.
Another alternative is atmospheric resonance due to coupling with magnetosphere resonance caused by impacting solar CME's, which have been occurring frequently over the last year. See the website below for related information. This recently discovered (thanks to NASA satellites) physics can couple the magnetosphere to the atmosphere to the lithosphere, with consequences that are still being investigated by physicists.
Finally, while it may be technically conceivable that HAARP technology can do something like this, I would be very surprised if it could be established as true.
http://spaceweather.com/ <---archive 1/19/12
CHANCE OF AURORAS: NOAA forecasters estimate a 15% to 20% chance of polar geomagnetic storms during the next 24 hours in response to a possible glancing blow from a CME. High-latitude sky watchers should be alert for auroras. Aurora alerts: text, voice.
INCREASING SOLAR ACTIVITY CLEANS UP SAT-DEBRIS: Earth's atmosphere has been puffing up in response to increasing levels of UV radiation from sunspots. This is good news for satellite operators, because a puffed up atmosphere helps clean up low-Earth orbit. "The number of cataloged debris in Earth orbit actually decreased during 2011," reports Nick Johnson in NASA's Orbital Debris Quarterly newsletter. "[The figure below] illustrates how the rate of debris reentries from the Fengyun-1C anti-satellite test of January 2007 increased during the past year."
Respectfully submitted,
Steve