The geek who captured the Castle

What MySpace did for indie rockers, YouTube is doing for the geek. When advertising executives saw a video of Boston theremin player Jon Bernhardt performing the old Buggles song ‘‘Video Killed the Radio Star’’ on YouTube, the MIT math grad was headhunted for the White Castle fast-food chain’s new advertising campaign.

Bernhardt, 43, who has DJ’d on WMBR’s ‘‘Breakfast of Champions’’ since college and played with indie rockers The Pee Wee Fist, works as an actuary for an insurance company. But it was when he saw a documentary on the theremin in the mid-’90s that he found his calling and formed the Lothars, which includes two theremins, electro-flute, and hammered dulcimer. The band celebrates its 10th anniversary this year.

‘‘They say that your instrument finds you,’’ Bernhardt says. ‘‘I saw that documentary, I thought I’ve got to get me one of those!’’

As one YouTube poster, ‘‘howlinjojo,’’ commented about Bernhardt’s take on the Buggles classic: ‘‘That is some quality geekage.’’

Q. What did you think about being headhunted by White Castle?

A. My first thought was that it was a prank. Then when I saw the casting call was genuine I was cautiously optimistic.

Q. And somewhat excited?

A. Oh yeah. The fact that they were tracking me down, I thought, 'Wow I've got a pretty good shot at this. ' I had a friend video a quick audition tape. I Fed Ex'd it to them. You know it's legitimate when they give you their Fed Ex number.

Q. Did you compose the song?

A. What they sent originally was a script with the lyrics but no melody. So what I came up with was like a blues call-and-response thing. Apparently they have a musicologist on staff who assured them that what I had done was free and clear.

Q. It didn't infringe on Big Bill Broonzy's copyright or anything?

A. Exactly. The absurdity is that I'm this nerdy white guy singing this blues song.

Q. With a theremin. Have you eaten White Castle?

A. I think I have. I grew up in New York where there are White Castles. I knew about them, but it's hard to remember.

Q. Did you know what a Slyder was?

A. Yeah, I knew they were tiny hamburgers.

Q. White Castle has cult, kitsch status. It has this retro cool.

A. It predates McDonald's. The ads go for that. I learned something very interesting from a woman at White Castle who fancied herself a White Castle historian. I was telling her about the Falafel Palace in Central Square. Everyone always talks about it once being a White Castle. But she said, 'Oh no, we never had a White Castle in Massachusetts. That must have been a copy, like White Palace.'

Q. Will the ads be on TV as well as on YouTube?

A. They will air over the summer, but I doubt they will air here.

Q. Advertisers are really trying to get a YouTube geeky vibe going these days.

A. Yeah. The conceit with this is that these are supposed to be people who write in and say how much they like White Castle. If you go to the White Castle website, there are people who actually do that. People send in stories. My story is 'I like it so much I wrote a song about it.'

Q. On a theremin! Are you a geek?

A. Oh yeah. I went to MIT! "

Q. White Castle and math geeks? Shouldn't it be guys who say "dude" a lot?

A. If you go to my ad you can see all the ads they've done. It's not just geeks. They get all types of people. There's one of a middle-aged woman doing a velvet painting of a White Castle.

Q. Would you do more ads?

A. It's hard to resist. They were so nice. I'm not about to move out to LA and try to be an actor though.

Q. Would you like to become the Jared of White Castle, the company's public face?

A. Playing songs on the theremin? We'll cross that bridge when we come to it.

Q. Maybe if they made you an offer you couldn't refuse?

A. Well, it's hard to refuse an offer you can't refuse.