A transit is when a planet passes directly between the Sun and the Earth and we see the planet as a small dot moving slowly across the face of the Sun. A Venus transit occurred in 2004 (see Venus Transit from GOES/SXI). Prior to that it was 1882. The last Venus transit occurred on June 5-6, 2012 and the next one won't occur until 2117 (See the NASA Eclipse Web Site).
To understand the significance of these events, it helps to know the history of how the Venus transits provided one of the first estimates of the size of the Solar System, and eventually the Universe (see A Brief History of the Transit of Venus).
In this visualization, there are a few things which should be noted.
1) The camera view is NOT from anywhere on the surface of the Earth, but corresponds to an observer positioned along the Earth-Sun line, but over the north pole of the Earth. This causes the path of Venus to cross the solar disk lower (closer to the solar equator) than it would appear to an observer on the surface of the Earth.
2) The ephemeris used for computing the planetary positions was not the high-precision JPL ephemeris (DE-421), but a lower-precision approximation. Yet, when tracked in detail, the transit takes place only about five hours later. It was decided that since the view of the transit in this visual does not correspond to any actual location ON the Earth, it might be misleading to present high-precision timing of the event.
This visualization was developed for conceptual illustration and not meant for precision scientific use.