Typical film damage effects. You can purchase footage to overlay or you can fake it with blurred shape layers and blend modes.
Scratches are also just film damage effects. There are a ton of tutorials and a bunch of stock film damage clips you can purchase.
Not all tutorials on YouTube present good info so you'll have to sort out the good from bad by trying to guess which folks have some experience.
Sorry for the late reply, but thank you for your help.
This is basically what I was looking for.
A good editor would never have used these defects while editing with film; they represent poor craftsmanship by the photographer. As a storytelling metaphor they represent tension (the end of the film roll reveals the assassin in the crowd) or they can literally depict the amateur status of a character's ability as a shooter. In music videos they're supposed to be a style. Boring.
Use with care. A wee bit of film damage or light leak effects goes a long way.