Though the term racism usually denotes race-based prejudice, violence, discrimination, or oppression, the term can also have varying and hotly contested definitions. Racialism is a related term, sometimes intended to avoid these negative meanings. According to the Oxford English Dictionary, racism is a belief or ideology that all members of each racial group possess characteristics or abilities specific to that race, especially to distinguish it as being either superior or inferior to another racial group or racial groups. The Merriam-Webster's Dictionary defines racism as a belief that race is the primary determinant of human traits and capacities and that racial differences produce an inherent superiority of a particular racial group, and that it is also the prejudice based on such a belief. The Macquarie Dictionary defines racism as: "the belief that human races have distinctive characteristics which determine their respective cultures, usually involving the idea that one's own race is superior and has the right to rule or dominate others."
The UN does not define "racism", however it does define "racial discrimination": according to the United Nations Convention on the Elimination of All Forms of Racial Discrimination,
the term "racial discrimination" shall mean any distinction, exclusion, restriction or preference based on race, colour, descent, or national or ethnic origin which has the purpose or effect of nullifying or impairing the recognition, enjoyment or exercise, on an equal footing, of human rights and fundamental freedoms in the political, economic, social, cultural or any other field of public life. '
This definition does not make any difference between prosecutions based on ethnicity and race, in part because the distinction between the two remains debatable among anthropologists. According to British law, racial group means "any group of people who are defined by reference to their race, colour, nationality (including citizenship) or ethnic or national origin".
In regards to the Obama clip, I cannot see any example of racism whatsoever.
However, I can understand how some people may think the intention was to offend, after reading this - also from Wikipedia:
Blackface, in the narrow sense, is a style of theatrical makeup that originated in the United States, used to take on the appearance of certain archetypes of American racism, especially those of the "happy-go-lucky darky on the plantation" or the "dandified coon". Blackface in the broader sense includes similarly stereotyped performances even when they do not involve blackface makeup.
Blackface was an important performance tradition in the American theater for roughly 100 years beginning around 1830. It quickly became popular overseas, particularly so in Britain, where the tradition lasted even longer than in the US. In both the United States and Britain, blackface was most commonly used in the minstrel performance tradition, but it predates that tradition, and it survived long past the heyday of the minstrel show. White blackface performers in the past used burnt cork and later greasepaint or shoe polish to blacken their skin and exaggerate their lips, often wearing woolly wigs, gloves, tailcoats, or ragged clothes to complete the transformation. Later, black artists also performed in blackface.
Stereotypes embodied in the stock characters of blackface minstrelsy played a significant role in cementing and proliferating racist images, attitudes and perceptions worldwide. In some quarters, the caricatures that were the legacy of blackface persist to the present day and are a cause of ongoing controversy.
By the mid-20th century, changing attitudes about race and racism effectively ended the prominence of blackface makeup used in performance in the U.S. and elsewhere. It remains in relatively limited use as a theatrical device, mostly outside the U.S., and is more commonly used today as social commentary or satire. Perhaps the most enduring effect of blackface is the precedent it established in the introduction of African American culture to an international audience, albeit through a distorted lens. Blackface's groundbreaking appropriation, exploitation, and assimilation of African-American cultureas well as the inter-ethnic artistic collaborations that stemmed from itwere but a prologue to the lucrative packaging, marketing, and dissemination of African-American cultural expression and its myriad derivative forms in today's world popular culture.
Finally, this quote about Blackface in Japan is very interesting
Blackface in the Japanese culture has developed with different intentions from other cultures, as it reflects a conscious embrace of African and African-American culture. According to Joe Wood, "they wear blackface in order to embrace black people." For many years the Japanese have appreciated African American musical styles, notably jazz, funk, rock n roll, and hip hop. Groups that have incorporated blackface into their act include Rats & Star and The Gospellers.
Japanese encounters with black people dates back to 1853 when Commodore Perry "re-opened" Japan and brought with him a troupe of minstrels. Much contact with American blacks took place after World War II. In reference to the experiences of African American servicemen in Japan, Ben Hamamoto writes, Many felt a noticeable difference being in a country that did not have a history of slavery, segregation, and white supremacy and found genuine curiosity more than prejudice colored their experiences with Japanese people.
Bottom line for me, the guy wanted his audience to know who he was impersonating, so he dressed like him and tried to do his make up as much like Obama as he could.