I work in media, have studied it for many years, and I can honestly say, I applaud those who want to go out the in search of answers. However, do so with an open set of eyes for both sides of the coin. Vids like the one in the link, while I appreciate their ability to make people question the truth, are usually just carefully constructed propaganda.
I'm not saying that one side is right and one side is wrong, and that there is no merit in what's being said. I simply want people to take into account a) it's incredibly easy to make any argument seem valid with the right interviews, editing and music and b) education is key. Before blindly agreeing with anything that anyone says, do some more research. There are a ton of resources out there that can help you get educated about all sides of any argument.
Sorry, just felt it needed to be said as I've just had this very problem with a friend of mine and her sudden love of conspiracy propaganda.