Personally, I don't feel the need for a Sim music video to have a story, but if it doesn't, it has to be set to music I like and/or be very visually impactful and edited very, very well (e.g., see Ooh La La below). I myself like a good dance video but it seems more people propagate toward Sim movies that have stories. The one issue with music videos w/stories is that for me to understand the story (I'm slow and not always so awesome), it often takes multiple viewings. With a beautifully filmed and edited movie like Helena, that's cool, I enjoy watching it again, but other films I find myself going "Huh?" without wanting to watch again.
There are breathtakingly beautiful ones at
www.britannicadreams.com. My favorite is "A Mermaid's Tale". I also like anything done by Tracechops at
www.simspremiere.com. Actually, all of those directors have made wonderful movies. Also check out "The Fixer" at
www.burntcoffeeprod.com. And finally, there are some very moving films at
Jovial Productions. Of course there are tons of good movies at Sims99, although you have to sift through them. For an awesome, eye candy dance treat, check out
Ooh La La.
Don't exactly mean to pimp my own stuff, but I've been getting into movie-making lately and recently made one called
Disco Duck that's gotten decent reviews on Sims99.