UFO Streaks by During Lightening Storm

From Youtube

Between Alma and Republican City in Nebraska on April 2, 2015. KeriLeigh Shriver saw this during a lightning storm found this low flying object in view. This repeats twice and then is slowed down to 1/5 the speed and zoomed in for a closer view. The National Weather Service was contacted, but what is it?

Online suggestions range from a Dementor from Harry Potter to the smoke monster from Lost.
Other theories include secret government test flight to inter dimensional creatures. Skyfish?

What do you think this is?