Level 3 Communications, a central partner in the Netflix online movie service, accused Comcast on Monday of charging a new fee that puts Internet video companies at a competitive disadvantage. Level 3, which helps to deliver Netflix’s streaming movies, said Comcast had effectively erected a tollbooth that “threatens the open Internet,” and indicated that it would seek government intervention. Comcast quickly denied that the clash had anything to do with network neutrality, instead calling it “a simple commercial dispute.” The dispute highlighted the growing importance of Internet video delivery — an area that some people say needs to be monitored...