Doctor removed from United Airlines flight files to preserve possible evidence Dao was seen in videos being dragged off a United flight.

 -- David Dao, the physician who was forcibly removed from a United flight, has filed court papers seeking to preserve and protect records related to the now infamous flight on Sunday night.

Among other records, the filing says preserving surveillance video, cockpit voice recordings, passenger manifestos, United company policies and incident reports are "crucial and essential" to ensure that Dao's case is not later prejudiced.

Videos of Dao being dragged down the aisle of a flight from Chicago to Louisville on Sunday sparked a furor on social media and prompted United CEO Oscar Munoz to apologize on Wednesday and promise that an incident like this “will never happen again."

"My initial words fell short of truly expressing the shame," Munoz said today in an exclusive interview on "Good Morning America."

He added that the feelings of embarrassment were "palpable" for him and his United colleagues.

"This will never happen again," Munoz said. "We are not going to put a law enforcement official onto a plane to take them off ... to remove a booked, paid, seated passenger. We can't do that."

Dao, 69, a resident of Elizabethtown, Kentucky, is a physician specializing in pulmonary conditions.

After the incident, he remained in Chicago to receive treatment at a local hospital for his injuries, according to a statement on Tuesday from his lawyers. It is unclear if Dao remains hospitalized.

United Airlines told ABC News that it offered passengers up to $800 in compensation to voluntarily give up their seats on the flight so that four crew members could board. The airline said that, when no one volunteered, the crew created a list of passengers that would be reassigned to another flight. This, the airline said, was in accordance with the airline’s contract of carriage.

Dao is said to be the only passenger of the four asked to leave the flight who did not comply.

On Wednesday, United Airlines confirmed to ABC News that it was compensating all passengers of the flight for the full price of their tickets.

One of the officers involved in Dao’s forcible removal has been placed on paid administrative duty pending an investigation leave, according to the Chicago Department of Aviation. The department said in statement Monday that the incident "was not in accordance with our standard operating procedure and the actions of the aviation security officer are obviously not condoned by the Department."

ABC News’ James Hill reported from Chicago. ABC News’ Whitney Lloyd, Jeffrey Cook and Michael Edison Hayden contributed to this report.