Yeah...that video was shot in the 80's. In SD.

Well, technically it looks like it was shot on film, so if they had the original film elements, they could scan them in HD. I think there's a better chance of Mike Love doing a solo version of "Smile" than Brother re-scanning the film negatives to the "Getcha Back" promo film, especially considering it's unlikely they kept any film elements.
Even watching the recent PBS "Doin' It Again" special, it looks like the "Good Vibrations" studio footage was the only old film element that may have been scanned in HD. Everything else like TAMI and the "Sloop John B" clip that were shot on film were sourced from SD sources.