The movies reproduce eye movements executed by participants reading vertically and horizontally drifting text, as reported in Valsecchi, Gegenfurtner & Schütz (2013). The red dot depicts the observer´s point of gaze. Depending on your system, the replay speed might be slower than the original (but so you can see saccades better).
The demos are also available as .avi files (Horizontal, Vertical)