Good way to teach French and personal safety! You surely wouldn’t just invite in a random person who says they are a postman?! Using little teaching snippets like this not only improves knowledge of and facility with French it can be a nice way to teach social skills and have a laugh at the same time. The expressions are useful and can be repeated . The video repeats them a number of times but so cn the teacher. In 10 minutes students would be able to say something useful in French without too much trouble.