Shadowbox

Shadowbox seems like a well-crafted, JavaScript media player.

“Shadowbox is a cross-browser, cross-platform, cleanly-coded and fully-documented media viewer application written entirely in JavaScript. Using Shadowbox, website authors can display pictures and movies in all major browsers without navigating away from the linking page. The default distribution of Shadowbox includes the full source code and a sample gallery (this file) that demonstrates how it is to be used.”