Complex sentence: U2 manager Paul McGuinness had long wanted to film the group for a concert video to highlight their success as a live act, and promote them to American audiences still unfamiliar with them.
Split into simpler sentences: U2 manager Paul McGuinness had long wanted to film the group for a concert video to highlight their prowess as a live act. McGuinness also wanted to promote them to American audiences still unfamiliar with them.