The video you are referring to was uploaded 1.8 months ago. Since then, the Angular team has significantly improved the Signal, and this method has been removed from Angular 18.

Mutate: This method was used to update signal value without replacing its original value, you can find more info by visiting Angular v16 Mutate.

Now we have two methods to update the signal value

• Update
• Set

Above both methods have slightly distant use cases over when to use which but both are being used for updating signal value, You can find more info from Angular's official documentation Angular-19 Singal

Thanks.