Ok, the two don't really do anything other than lend the song 'Without You' to the UN Foundation and OCHA. It has garnered more than three-quarters of a million views in two weeks time. Listing the song name at the front probably helps as it draws in fans who want to listen to the track.
The video itself features an Australian brother and sister who visit a family affected by the drought in Niger. Its premise is to tell the story of people affected by the drought by going beyond the tragedy dominated headlines.
The content itself could be discussed, but I wonder how effective it is at grabbing a new audience. The celebrities are used as a facilitator through what they do best, make music. For those who are critical of celebrity-driven advocacy, this may be a step towards campaigns that use but do not feature celebrities.