You know when a franchise spreads across a bunch of different platforms, finding new ways to entertain (and make money from) audiences? – That’s transmedia storytelling. Each medium that the story is shared on is an extension of the experience, offering up new additions to the plot.
The advantage of transmedia narrative is that people can join in from varying entry points, making it easier to gain a following. Multiple companies have incorporated this method into their productions; with large companies like Disney taking advantage of their large franchises like Star Wars and Marvel. This strategy can be used to draw people into a large production, or keep an established audience interested with smaller spin-offs.
From the tens of thousands of fanfics, to the many people playing the graphically-challenged games from the beginning of this millennium, YouTube is home to a vast array of Harry Potter material.
The beauty of transmedia storytelling is the way the audience themselves can produce the bonus content. YouTube allows both the companies, and fans to share unique additions to a potentially massive audience.