Is 'Blackface' always racist?

The American media have come down hard on a French journalist at Elle magazine. Jeanne Deroo put a photo of herself on Instagram dressed as Solange Knowles. US media call the phenomenon "Blackface" - white people dressing up as African-Americans. In France, the photo has caused less upset but the journalist has apologised nonetheless. Also, a Brazilian satirical website fools French media into believing a fictional story. Finally, a superb film composed of 852 Instagram photos goes viral.