Do you know where it is in the video? Are they not talking about something like this?

    public bool IsOpen{get; private set;}
    public void Open(){
        try{
            // do some complex work
            this.IsOpen = true;
        }
        catch{
            this.IsOpen = false;
        }
    }
    public void Close(){
        // do some other work
        this.IsOpen = false;
    }

Not sure about the minute, the video is prohibitively long...

It's on the 9th slide: https://view.officeapps.live.com/op/view.aspx?src=http%3a%2f...

I see. Maybe they mean "implicit private set"? Otherwise, one of the sibling comments has a good point about the binary compatibility issues with fields vs properties.