Anthony David McPartlin  (born 18 November 1975) is an English television presenter, producer and actor. He is best known for working alongside Declan Donnelly as part of the presenting duo Ant & Dec. McPartlin came to prominence, alongside Donnelly, in the children's drama series Byker Grove, with both men establishing successful careers as television presenters, in which they are most known for presenting SMTV Live (between 1998-2001), I'm a Celebrity...Get Me Out of Here!

McPartlin's first appearance on television was on the children's workshop programme Why Don't You?, but his big break came when he rose to prominence playing the character of PJ in the CBBC series Byker Grove. It was during his time on the programme that he first met Declan Donnelly, who was cast in the part of Duncan. The pair formed a close friendship on the programme, both socially and professionally, with the men performing as their characters until their departure from the programme in 1993. During their tenure, the pair created a number of hit records under the label of "PJ & Duncan AKA", including the song "Tonight I'm Free" that had been performed on Byker Grove.  From that part onwards, McPartlin and Donnely worked together on television, creating the presenting duo of Ant & Dec. Initially, the pair continued to work in children's television with the Saturday morning hit SMTV Live, before they eventually branched out into gameshows - Friends Like These, PokerFace and Push the Button - along with talent shows - Pop Idol, and Britain's Got Talent - and entertainment programmes - I'm a Celebrity... Get Me Out of Here!, and Ant & Dec's Saturday Night Takeaway. The pair continued to maintain work in acting, starring in a tribute to The Likely Lads, in the form of a remake of an episode from the show's sequel Whatever Happened to the Likely Lads? entitled "No Hiding Place". In 2006, McPartlin and Donnelly starred together in the film Alien Autopsy.  In 2007, it was discovered that two shows, Ant & Dec's Gameshow Marathon and Ant & Dec's Saturday Night Takeaway, which he co-presented with Donnelly, had defrauded viewers participating in phone-ins. The latter was produced by the pair's own production company.  In April 2009, Ant & Dec achieved wide international exposure when, as backstage commentators for Britain's Got Talent, they interviewed contestant Susan Boyle, whose audition would become the most viewed YouTube video of the year and whose record album topped sales charts in dozens of countries.

Using a quote from the above article, answer the following question: What was a hallmark of his career?
for Britain's Got Talent, they interviewed contestant Susan Boyle, whose audition would become the most viewed YouTube video of the year