No, but Look Back will not allow you to fast-forward some programming like a DVR can. Also, Look Back programs can be viewed up to 3 days after they have aired, whereas DVR customers can store and view their recorded programs for as long as they like.
To receive all services, Digital Cable, remote and lease of a digital set-top box are required. Some services are not available to CableCARD™ customers. Not all equipment supports all services. Look Back® is available on select shows from participating networks. All services and channels may not be available in all areas. Subject to change without notice. Some restrictions apply.