A Manhattan video editor attending a New Year’s Eve office party was viciously attacked with a champagne bottle by a party crasher, authorities said.

“I lost about a liter of blood and an artery was cut. It could have been a lot worse,” said William Znidaric, 36.

Znidaric said that at about 3 a.m., he spotted one of the unidentified intruders outside the building as the party broke up — because he had carried out a bullhorn stolen from the SoHo office on Grand Street at Lafayette Street.

The horn had been used as a prop to count down to the New Year.

Sources said the bullhorn thief was standing with several pals who’d also crashed the affair.

Znidaric confronted the thief, whose pal smashed him with the bottle.

“Next thing I know I’m eating the sidewalk. I didn’t see it coming. I saw stars,” Znidaric said.

Znidaric sustained a gash to his head that required 15 stitches.

The assailants fled.