Calculate speed of a moving object in video

I'm tracking a statue in a dark room with a "Light-emitting diode" attached on top of it. It's easy to keep track of where in the room the statue is but i want more.

The plan is to generate white noise(for a start) that is sent through a low pass filter. Then I want to keep track of how fast the statue is moving in the room. The movementspeed of the statue will then control the cutting frequency of the filter. Higher speed equals higher cutting frequency. This will create nice "swoching" effect.

But is this possible without an accelorometer. I don't know how but I want to learn how and I really think someone here knows how. Please forum, I know you can help me.

I bet it's easier than it looks.