Earth, Moon and Sun
Day and Night
Equinoxes:
Equinoxes and Solstices explained (video)
Seasons:
Movement and position of the earth (video)
Why do we have different seasons? (video)
Bill Nye explains the seasons (video)
Northern Hemisphere Summer Solstice
Northern Hemisphere Winter Solstice
Eclipses:
Solar Eclipse simulation - click simulation in the menu
National Geographic Solar Eclipse (5 mins)
National Geographic Lunar Eclipse (3 mins)
Moon Phases
Near side and Far side of the moon explained (required viewing to 2:15 in the video)
Exoplanets:
NASA's Eyes on Exoplanets - web version
Extras:
Star Size Comparison (cool video)
Wanderers (cool video)
Powers of 10 (cool)
National Geographic The Story of Earth - first 10 minutes (video)
Carl Sagan Pale Blue Dot (video) - my favourite quote "momentary masters of a fraction of a dot"