Barca are hoping to win the competition for a fourth year in succession and had little difficulty seeing off Murcia, with Vidal – very much a fringe player at the club – catching the eye as Ernesto Valverde's men booked their place in the last 16.
Paco Alcacer scored the opening goal after good work from the former Sevilla wing-back, though it was one of very few highlights in a tepid first half.
Barca stepped things up several notches after the break, playing with much greater attacking intent and they ultimately blew their visitors away.
It came as little surprise when the second goal came, as Vidal set up Gerard Pique before then getting himself in on the act with a fine header.
Denis Suarez and youngster Jose Arnaiz completed the rout late on, sending Barca through in emphatic style.
As expected, it was all Barcelona during the early exchanges and eventually they crafted a meaningful chance 16 minutes in, which was buried to end Murcia's resistance.
Vidal darted into the penalty area and his shot was deflected into the path of Alcacer to nod past the helpless Alex Santome in goal.
The hosts should have doubled their advantage a couple of minutes later, but Gerard Deulofeu horribly miscued his close-range volley when reaching Nelson Semedo's cross from the right.
Chances were otherwise hard to come by, particularly for the visitors with Barca dominant.
Barca began the second half with more urgency in the final third and quickly crafted an opening, Suarez embarking on a mazy solo run before finding Alcacer, whose eventual effort was well blocked.
Deulofeu let fly shortly after, producing a lovely turn prior to hitting the post from the edge of the area.
But their second eventually arrived in the 57th minute, as Pique tapped in a Vidal cross from close range, before then heading off as if scoring was his sole purpose.
Vidal took the captain's armband from him and got a goal for himself a few moments later, producing a brilliant looping header from Semedo's delivery.
Suarez joined in 16 minutes from the end, playing a wonderful one-two with Sergi Roberto and applying a cool left-footed finish from 12 yards.
And Arnaiz rounded things off in the 79th minute with a lovely left-footed strike from the edge of the area, his first goal for the first team.
