From the YouTube description:
Tornado Sucks Up Tractor Trailers In Dallas Texas 4-3-2012 Raw Footage Tornadoes ripped through the Dallas-Fort Worth, Texas area Tuesday afternoon, launching tractor-trailers into the air as if they were children's toys. As a tornado spun through an industrial area in Lancaster, Texas, about 15 miles south of Dallas, it wreaked havoc on a fleet of trucks, perilously tossing them dozens of feet in the air.
Severe storms brought golf-ball-sized hail and led to the touchdown of at least two tornadoes in the region. The skies darkened to a night-like level as the storms rushed in. A number of injuries were reported and homes damaged in the heavily-populated suburbs south of Dallas and Fort Worth.