[jpxxx]

Sounds right, good sleuthing, thank you. This machine has an Intel 3000.

The stars appear properly placed, but instead of a point there's an effect-ruining translucent square around each one. The single-pixel distance lines also look wrong during transitions.

Since this mystery ends in a Radar ticket about GPU drivers, I won't hold my breath for a fix. As far as Apple is concerned, it ain't broke until Final Cut is broke.