A 30-second video of a United Airlines passenger being dragged from his seat and bloodied on an overbooked Sunday flight at O’Hare International Airport racked up more than 6 million views Monday and sparked plenty of outrage. For United, the video threatened to unravel more than a year of work by CEO Oscar Munoz to rebuild the airline’s battered customer service reputation and prompted questions about why United didn’t try harder to fix the situation rather than apologizing afterward for having to “reaccommodate” passengers. It was also the second time in two weeks that Chicago-based United took a beating on social media, having previously been chastised for not allowing two teens wearing leggings — a violation of a dress code for employees and guests traveling on the company’s dime — to board. For the flying public, the episode served as a stark reminder that a seat isn’t guaranteed until a flight is airborne. Almost half a million passengers on major U.S. airlines got bumped last year but most of them volunteered to lose their seats in return for credits for future flights. United confirmed Monday evening that passenger ran back onto the aircraft after being removed.