There is not such thing as casual or mild racism. It is racism. Imitating a persons accent in this manner is racism. Making, for want of a better word, 'fun' of another's accent is racism. Racism is cumulative and it is very damaging both individually and to the wider community. Trying to trivialise acts of racism is racism. It is not hard to treat ALL people as equals and not objects of ridicule and bigotry even if the target brushes it off you have no idea of the pain you inflicting and the damage you are inflicting due to a life time of this behaviour. The announcer let his real self slip when he slumped into his stupidity. It was not trivial it was transmitted over several media therefore the impact had a wide audience. It is very sad that folks cannot recognise this. Have the events of the 21st century to date not taught you what the harm of racism does to individuals and societies?
Some have asked for education, here goes, its not hard...."prejudice, discrimination, or antagonism by an individual, community, or institution against a person or people on the basis of their membership of a particular racial or ethnic group, typically one that is a minority or marginalized."