His family were considered Venetian nobility, having purchased titles and positions from the city of Venice which was keen to raise money to fund their role in the War of Candia.
According to contemporary John Bargrave, it was tradition for new popes to retire those who purchased senior clerical positions by elevating them to cardinal. So it was, when Pope Innocent X was elected at the papal conclave of 1644, that Vidman was relieved of his positions to allow the new pope to sell them to prospective young clerks.[2] Vidman, then, was elevated to cardinal in the consistory of 7 October 1647 by Pope Innocent X and was installed as cardinal-deacon at the Church of Santi Nereo e Achilleo.
Despite his elevation to cardinal, he and his brother, now a count, still delighted, "in gaming, feasting, comedies, and the company of women".[2]