According to the video description, this onlooker captured the moment that a truck transporting what is believed to be a nuclear weapon was rear ended by one of its escort vehicles!
The incident took place on US-89 in Great Falls, Montana about 5 miles from the Malmstrom Air Force Base. Eyewitnesses said that several helicopters also accompanied the convoy.
No one appears to have been injured during the incident.
If you are having trouble viewing the video, follow this link to the original.