This will certainly make you want to head for your own viewing spot to watch the sunset.

FORBES: The World's Most Celebrated Sunsets

They also tested whether the learning process was conscious by distracting the subjects during the video viewing - the volunteers were asked to do simple arithmetic sums in their head, for example.

BBC: Image of golfer Tiger Woods

Vodafone is also running several pilots, says Richard Saggers, the head of its mobile advertising unit, in which subscribers receive free content in exchange for viewing ads.

ECONOMIST: Mobile advertising