It's pretty funny that in this thread of over 45 posts there's about 10-15 different ideas as to what it really is. I've watched the vid probably 20+ times and still can't really get a grasp on what it might be. I originally thought the object actually disappeared behind the treeline and the little streak in front of the treeline was just an optical illusion due to low camera resolution. However, the more I watch it the more it looks like it is in fact in front of that treeline.
One thing that makes me think this was something unrelated to lightning is the fact that I've never seen anything like this before on camera or in person. Think of all the lightning we've all witnessed in person, and on video and none of us have ever witnessed anything like what appears to be in the video here. Just seems a bit odd that something could be so rare as to not be captured by film until now out of all the storms that get recorded.