it is never justifiable to believe in some proposition without sufficient evidence for such proposition
that;s the moral of that video.
There are always going to be certain areas of individual's lives where they don't apply this princple. It's psychology. It might even be beneificial in some circumstances. Sometimes you need to narrow your horizons long enough to follow one path to any significant degree without having to stop and reconsider basic premises. To ask people to examine every part of their being at every moment is similarly a bit rude. Prejudice gives life a certian purpose, flavour and mystery.