Liverpool won the game 4-1 after United took the lead with a penalty goal from Cristiano Ronaldo.
Vidic was shown a straight red card for brining down Steven Gerrard and the visitors scored on the free-kick.
“It was a nervy start from both teams but we took the lead and started to get a foot in the game,” Ferdinand told MUTV. “Even when they were 2-1 up, we started to turn the screw in the second half and Carlos Tevez had a half-chance.
“But the sending-off and third goal came at a really critical time. I thought the referee’s decision to send Vida off was debatable as I could have got over there to cover.”