Every so often, Hollywood reminds us of how silly it is to argue over whether giving away content will result in a loss of overall sales — because they’ve been doing it successfully for years. This week, director Christopher Nolan released this 13-minute viral video promoting the upcoming film The Dark Knight Rises in which an estimated 10 minutes of fragmented film footage is made available absolutely free of charge. A bold move to be sure, and one that may have made Warner Bros execs sweat a bit at first. But how risky was it, really? Are fans likely to forego the actual film come July 20th (No thanks, Warner Bros , 10 minutes was plenty!) as a result of Nolan ’s generous offering? Of course not. The Dark Knight Rises…