The changes can be so drastic that little—if any—evidence of the TV show or movie's true origin remains.
For television documentaries, it is an established practice in English-speaking countries to hire someone of the audience's accent as a narrator.
Sometimes the script is done verbatim, e.g., the PBS Nova documentary series continued to use the BBC's original word "maize", whereas an American audience would expect to hear "corn".
Examples include Godzilla, Point of No Return (aka Nikita), My Father the Hero, The Office, The Ring and House of Cards.
An example of this is Power Rangers, which uses an English speaking cast playing new characters and dubbing over stock footage from its original Japanese counterpart Super Sentai.