This may be a regional thing, but i would replace the "this" for "that".
I live in the North West of England and a lot of people do say:
"Don't get me started on that. I will be talking for hours"
"Don't let me get started on that, I will talk for hours"
Both would infer that the person is very passionate on the subject that has been brought up.
For example;
Person A: "Have you heard about the police on the news?"
Person B: "Don't get me started on that. I will be talking for hours!" or of course, "Don't let me get started on that, I will talk for hours!".