4:33 video

You're possessed and doing a crazy face like the movie SMILE

(Head tilted backwards, eyes open big looking at the camera and big full top teeth showing smile).

Importantly be crazy looking.

Doing the face because you want cum (not cum on your face or anything like that, more like how a thing has deep desire for it in general)

Have no makeup on (the more unconventionally unattractive you can look and crazier the better).

Camera very close-up on just your face throughout.

And low down (to make your eyes look bigger).

Start by having your eyes closed, then quickly opening them and saying "I want cum" (speak in a deep demonic type of voice) and do the crazy face.

Tell me to stare at your face and to jerk my cock fast, but to not stop until I cum.

Encourage me to have an orgasm. Where someone masturbates non stop, so to bypass the edging process and make the cum out (is difficult to do and similar to a ruined orgasm, so is like a evil instruction and hence the evil crazy face).

Basically keep doing the crazy face and encouraging me to keep jerking my cock to your face non stop until I cum.

Stare at the camera.

Use key words "face", "cock" and "cum".

So for example say sentences with those such as

Stare at my face and make your cock cum.

Repeatedly say things like that.

To mix it up you can exchange stare for look, your for that and adding in the words keep and fucking.

So for example 

"Keep staring/looking at my fucking face".

"Fucking make your/that cock cum".

"I want that/your cum from your hard cock".

Towards the end, just be speaking more intensely.

Don't tell me when to cum, just repeatedly to cum (because I could cum at anytime)