If a set top box or a cable modem forms part of the equipment, you should take reasonable steps to make sure that, while it is not in use, the electricity supplied to it is not turned off and that it is in a standby or rest mode (unless we advise you otherwise).
Ah yes, that’d be the infamous standby state. The existing version of the NTL terms of service is currently here (October 2006 revision) and does not contain any such stipulation so it’s a new Virgin addition. Part of being a well respected brand and company is that people expect you to have a coherent worldview and carry that across everything you do. Currently they’re not.