YouTube - The primary place my film feature is YouTube because it is the largest video-sharing website on the internet and there is a big presence of short films on there. Having a YouTube channel and uploading your films to it is an excellent thing to do because you can build an identity as a filmmaker as all of your films will be in one place. People can share the film easily with their peers on facebook, twitter, and other social media very easily, and it will directly link people to your content. Also, audience feedback is easy to collect due to the comments section of YouTube. It can also ignite debates about about the film and get people interested and talking about it. Here, Christopher Nolan's new film, Interstellar, is being marketed through YouTube by having its own YouTube channel featuring short advertisements and different trailers.
I could use twitter to promote my film in the same way, either by having an account specifically for the film, or my own to promote myself as a filmmaker. Twitter is better than YouTube for getting people talking about a product because all tweets about it can be linked via a hashtag (#GoneGirl), therefore I can enter a hashtag, such as #GoneGirl in the search bar and instantly see audience feedback.
Facebook - is also used by many independent filmmakers and Hollywood studios to promote their latest releases. This is much the same as what they do on twitter, but Facebook now has an appeal to the older generations - not just teenagers, so there is a bigger audience to attract.
Facebook could be very useful in the promotion of my film because it can reach a large audience quicker than on twitter as when a post is 'liked', it is shared with that user's Facebook friends, on their timeline. Also, users can directly share the page or its posts with their friends in a few clicks. Furthermore, Facebook does not update as often as twitter so posts on people's timelines stick around for longer, meaning there is a greater chance of them being seen.
As an example, here is The Hunger Games' promotional Facebook page: