Calling Trump a racist didn't work the first 687 times but maybe...
That's because Republican primary voters don't care. The general electorate is very different, and videos like these could be used to jack up minority turnout even more. They will not see things the way Trump supporters do, obviously.
The general electorate isn't going to take the attempted tarring and feathering of a major party's nominee well, especially in an election cycle defined by the question of political correctness. It's too transparent, and if anything, will push undecided whites over to Trump.