It seems like the common thread is that White America has been looking for an excuse to exploit and mistreat non white people since the beginning of the country. I think it is easier to mistreat people if you don't recognize their humanity and a common thread through these videos has been the unwillingness of white Americans to respect people who are not white Americans as having the same feelings and human responses as they do.
I think this is present in today's culture as well. Making an excuse for mistreating almost seems justifiable and defendable...what the country is not realizing is that every person is deserving of the same respect.