Video with Fast Forward of Not?

I'm seeing more and more videos on sites without giving you the option to fast forward. While I find it annoying if I cannot fast forward, I've heard the conversions are a lot better if someone watches your whole video. Is there any concrete EVIDENCE that this is true?

As a video watcher I want the option to fast forward. Even you state "I find it annoying if I cannot fast forward". Design the website that a user will want to visit, not a website that annoys everyone.

If you don't want to allow fast forward, then don't put a video with a boring intro. People lose interest very fast.

This is my opinion based on the way I browse the internet. Goodluck with your decision.