Visualization of Global Cargo Ships

This is a really satisfying animation to watch. The thick, bunched-together lines of ships all turning the corner at some cape or strait really show you how the cargo is moving.

Does anyone else understand the UI? It does not make sense to me: the giant "play" button blocking the middle of the display seems not to play, but to stop playing, replacing the moving-dot animation with colored streaks. Clicking it again causes the map to zoom out! Then I reloaded the page, and this time instead of trying to click the giant "play" button, I clicked "options", which did not bring up any options, but did move the "play" button out of the way to the corner.