Advantages

1. Easier for the regular person to voice their opinion.  For example with trailers and comments on youtube.  SPECIFIC EXAMPLE FROM YOUR CASE STUDY.
2. find out information more easily eg:  views, trivia, information about the films.  For example, wikapedia articles.  IMDB for miscellaneous information. 
3. You can share your life with people.  For example on Twitter and with photos.  Social interaction and discussion.
4. Validation of your existence and self esteem booster.
5. if you want to be famous it's easier.
6. You can share your interests and meet other people who have the same passions as you.  youtube posting comments back and forth.  Vital BMX - so people with a similar niche interest can easily find groups of likeminded people. 
7. For some people they may see it  as freedom to act in a way that they want and to be able to say what they want.   Gives people confidence because they can be anyone that they want.
8. Allows another platform to access Media - you can watch things on the internet more easily

Disadvantages
1. Althoguh opinions can be stated on the internet the sheer volume of users causes many peoples opinions to be lost among the numersous arguments that may have sprung up due to people voicing there opinion in the first place.
2. Whilst there is a wealth of information on the internet much of it is able to be altered by anyone either directly or indirectly such as altering wikipedia articles or skewing reviews by posting negative (or positive in some cases) on multiple accounts.
3. People can effectively influence the ways that people veiw them by posting only hte highlights of their life. Also the fact that many people post large amounts of informaiton people post to a website where anyone can access it, even by possibley masquerading as a freind, can only be a bad thing.
4. People can become obssessed with being the centre of attention even on the internet leading to them spending a vast amount of time posting about themselves and also people can lose self esteem if people dont show an interest in what they have posted.
7. The ananonimty of the internet allows people to post offensive content with no consequences (Although there have been court cases recently over offensive comments made via twitter and facebook in the uk.).