One of the benefits of the cloud DVR service is that it allows access to your DVR programs outside of the home via a mobile device. Cloud DVR service is included with X1 at no additional charge.
Some details below on the Cloud DVR feature:
Apologies. We don't currently have plans to activate the e-SATA port for external hard drives on our X1 platform.
to make my cloud DVR work (have 3 DVRs) they said they had to charge me $10/month as an 'anyroom DVR fee'. Not quite free it seems.