Level 3 today raised alarms with claims that Comcast was engaging in anti-competitive behavior with a new charge for online video. The Internet backbone provider said that Comcast had suddenly started charging extra for video to its customers and threatened to block video traffic from Level 3, which supplies streams for Netflix and other major providers. It agreed to pay the fee to avoid a disruption but accused Comcast of setting up a "toll booth" deliberately designed to prevent competition with both cable TV and its own Internet features