Looking at the video, I believe too it is strobelights. However it could also be an engine surge as well - but that should not bring a 737 down. The final flash looks to me like an other lightning - like comming from the depature direction.
Overall the video until now gives more gueses than facts.
If there had been any fire I would have expected some burning fuel at the surface, but until now there has been no evidence of a fire - unless I missed somthing???
Walder
