A 14-minute video recorded on March 29 by witnesses in a vehicle behind the pickup also shows the 2007 Dodge Ram 3500 cross completely into the wrong lane of the two-lane state highway once and go off the shoulder into the grass at least five times, the report says.
The recording does not show the collision between the northbound pickup and the southbound bus, which was returning from a retreat in the Hill Country, when the pickup crossed over into its lane.
Thirteen people on the bus were killed in the crash in Uvalde County. A female passenger in the bus and the 20-year-old driver of the pickup survived.
The pickup driver, who was hospitalized for six days and has not been charged, told NTSB investigators he was checking his phone for a text when the crash occurred, the report says.
"The driver also told NTSB investigators he had been taking prescription medications prior to the crash. Several of those medications, as well as marijuana, were found in the pickup truck at the scene of the crash," the report says. "Toxicology test results are pending."
The crash victims -- the bus driver and senior members of First Baptist Church in New Braunfels -- were wearing seatbelts.
NTSB investigators estimated the pickup truck's speed to have stayed between 67 and 71 miles per hour on the state highway, where the speed limit is 70.
The report doesn't give a cause for the accident and says the investigation is still looking into the pickup driver's phone records, toxicology results from a blood sample and data from vehicle computers.
On the day of the crash, at least three calls were made to 911 dispatchers reporting an "erratic driver" prior to the accident, officials have said.
Real County Constable Nathan Johnson said that the first call was made by a motorist who reported seeing the pickup truck driver operating the vehicle in an "erratic" way. Real County officers were out looking for the vehicle.
Johnson said another call came in to Uvalde 911 operators about the same vehicle.
The next call to emergency officials reported the crash between the minibus and the pickup truck.
The bus was a Ford Econoline 350 van that had been converted into a bus -- a common modification.