This hard drive contains software like Adobe's Font Collection, a 124GB music collection, tons of games, books and more. All the files were downloaded illegally and is supposed to represent, I'm assuming here, the freedom and/or piracy of art.
The art installation, called "5 Million Dollars, 1 Terabyte", is being displayed at the Art 404 Gallery. This is probably super mind-blowing to old people but I'm sure some of us (maybe all!) have a few gigabytes we wouldn't want audited by the pirate police. Look at the full list of stuff loaded onto the hard drive here (PDF). [Art 404 via The Next Web]