Angry Birds Trailer - Why parodies are becoming more believable

RoosterTeeth's latest creation, Angry Birds: The Movie was put online as a parody trailer for a popular game available on the iPhones, iPads and also Android Phones recently. Although this was supposed to be a fun trailer for people to watch and enjoy, many bombarded RoosterTeeth asking for information on its release and how they were going to film it.

So my question is, on the internet what can you actually believe to be real (like films being released, information given etc.) and what is just for fun (like the angry birds trailer)

It been a long running problem on the internet with information been released  on it is its lack of validity and truthfulness. Wikipedia is one of the most famous examples as its a website which can be changed and edited about anyone who visits the website. This caused many problems with people as they believed that some of the information that was added to be true when infact they were edited for people's own malicious reasons.

For example Vernon Kay had to report to the police in 2008 when an editor said on Wikipedia he had died in a boating accident. Even close members of his family heard about it and questioned his wife and family.

So on the internet how can we tell if something is true or fake?