"Don't Kill Your Friends" is a 1943 Navy training film starring Huntz Hall. Not killing your friends can be very good advice depending, of course, on who your friends are.
In 1943, Huntz Hall had stopped appearing in Dead End Kids comedies and had begun appearing in East Side Kids comedies. He was a pretty reliable comedy talent who appeared in an awful lot of films and TV shows during a career that stretched from 1937 to 1993.
The Internet Movie Database and the fellow who uploaded this video to YouTube identify the uncredited narrator of this film as Daws Butler, the great cartoon voice actor and one of the nicest men it was ever my pleasure to know. They're wrong. I dunno who the narrator was but it ain't Daws, who didn't really get started in voiceover until he moved to Hollywood in 1948.
In '43 when this film was made, Daws was in the Navy but like I said, that ain't him. I've had very little luck correcting the IMDB over the years but if some reader of this site is better at it than I am, please let them know…