I don't know how this "watch this for PEDs"-stuff works or is handled, but I can't come up with a way that's safe for you as the consumer.
You should know that they either have to give you PEDs directly when you say that you will watch the video, or you will be required to leave your in-game info in some form on the offered site.
What you need to know about the latter way is that you really need to take a lot of care there. Just think of how they are supposed to give you the PEDs as their site is in no way associated with EU. It cannot be as EU is a closed system. If FPC, RT or MA is promoting something, you can be sure that you can find something about it either here on PCF or on one of their news-pages.
Anyway:
- you may end up providing your in-game username only. Well, then you are required to find the promoter you met in-game again and convince him/her that you watched the video. To be honest, I don't think anyone does this.
- you may end up providing your in-game username AND your password as they want to transfer the money directly to your account (or whatever words they use). If that doesn't sound fishy, I don't know what I need to tell you: you tell them your login-info and they own your account.
Furthermore, don't forget that such a site can be full of evil things that try to invade your PC (virus, worms, malware of any kind).
To be on the safe side you could just try to find that person for several consecutive days. If that person or anyone else is always promoting the same site, it might not be bad (note that this doesn't make it 100% secure).