He wrote the song out of devotion to his mom. I'd say the video means that he'll find her and serenade her at all costs. Even if he's missing half his body.
This video is so many things that shouldn't go together. It's uplifting, disturbing, sweet, comical, bright, dark, odd, ugly, adorable.. it's a lot of things. But I like it. I just love this band in general.