Disclaimer: I am not very well versed in statistics and have only just read the Wikipedia article on Instrumental variables.
On page 14, the report discusses the model they use, which is a linear system of the log of the four variables they're trying to find relationships between. They then discuss 4 instrumental variables as well as two dozen or so dummy variables that describe aspects of the actual show, like when it is aired on TV, whether they have related drama CDs, net broadcasts, whether the anime was an original work or based on manga, novels, games, etc., who the target audience was and how many regions the show have been broadcast in. Table 3 has the full list, and also includes what I assume to be slopes in log-log space from their analysis as well as a "t" factor for which I'm not sure about. The four main instrumental (non-dummy) variables are: DVD price (number of thousands of yen per episode, how long a video on YouTube persists ... while the series is airing, within 1 month of that particular episode airing, and after the series is finished airing).
Table 4 is a chart highlighting that there is a negative correlation with DVD price and DVD sales, but a positive correlation of DVD price and YouTube views. There were also positive correlations between how long a video managed to stay on YouTube after airing of the TV show has been completed and DVD sales, rentals and YouTube views, but a negative correlation with Winny downloads.
According to Wikipedia, use of instrumental variables is one way to see if there is actual causation between two variables. However, I'll leave it to someone more well-versed in the subject to see if the report is accurate or not.