I've seen a few versions of Beyonce's Single Ladies in my time. This gets a special nod because of the number of people, folksy venue, and distracting lack of pants. Oh and there's a really cute proposal at the end.
Through both work and personal preference I've seen a lot of Bollywood in my time. Combining dance AND a capella singing? Coming from someone who can barely chew gum and walk at the same time, that's just pro.