For a list of short films try this web site: http://www.irisprize.org/
While, the 2013 shorts are not available, some trailers can be found on YouTube. There are tabs for shorts from prior years. There's a likelihood that trailers exist for those films.
Another option is to google Gay & Lesbian / LGTB film festival websites and rummage through the offerings. Trailers can be found to review for rentals or purchase. Sometimes, the entire movie has been posted on YouTube.
Two video companies producing gay & lesbian films are Wolfe Video: https://www.wolfevideo.com/
and TLA Video http://www.tlavideo.com/gay/2
. The TLA site sells videos from many other companies and offers video on demand. This should be a good source to get titles for trailers.