Oh noes! UFOs!

Or it could be a lot simpler. They are humans from the future that used to Sling-Shot effect, like in Star Trek, and went back into time to do research to make sure that there history books were correct. Unfortunatly, the the slip through the fourth dimention caused system errors that caused the Warp Celestial Guidance sytems to go off-line for a few moments causing them to go off course. With the large amount of tachyon radiation interfering with the cloaking device caused them to become visiable. However, the main sensor array was not damaged and alerted the Main computer (I would have to say it was before the Daystrom Duotronic Processor) and engaged the Impulse drive (from the video I would have to say it was a standard SBE Subatomic Unified Energy Impulse Unit because of the visiable trail it left in the atmosphere) veering them back into a high standard orbit keeping them out of detection from our primitive RADAR systems and other means of detecting them. But, looking at the video more closly it looks very simular to the Borg scouting vessals, that would explain the visiable green light. That would mean that the ships were capable of Transwarp (I could make out possiable Transwarp Coil Assemblies) ,thus, giving them the ability to cross interstellar distances at a Warp Factor of 10, meaning, it would take no time to cross the huge distances. This is only speculation of course, but it came from a hard-core trekkie, so, i cant be too far off. (Sorry for the long post, but, sometimes i cant help myself)