The problem with the DMCA is that even if you follow the law to the letter, the content industry can persuade the courts that your business does not comply based on "knowing or *should* have known" it was used to commit the infringement copyright. Such a court decision can shut anyone down if the MPAA/RIAA don't like you.
Also, Youtube is loaded with infringing full length movies, many from Disney, etc. They auto play these films for you all the time with their interest algorithm. They are hardly angels. ContentID appears to be extremely biased who it hits.
