After announcing their happy news, James gushed that he was 'over the moon', adding that he and Julia 'couldn't be any happier'.
The video has since gone viral, with TV presenter James Corden - well-known for his Carpool Karaoke with celebrities - revealing it moved him to tears.
He was previously linked to celebrities including Lily Allen and pop star Alexandra Burke.
Corden and Carey seen in December before they headed off on their holidays James previously appeared in teen soap Hollyoaks but got his big TV break in 2000 when he landed a regular role in the ITV1 series Fat Friends, where he met Gavin And Stacey co-star Ruth Jones.
James and Julia were introduced by his former flatmate, actor Cooper, who appeared with James in the stage and film versions of Alan Bennett's play The History Boys.
The pair confirmed they were expecting their first child together at the end of September.
The couple welcomed their third addition in December, and James joked on his US chat show that Charlotte was very nearly named Beyonce.