Replication from Backup Off-host Proxy?

[tcross]

I am wondering, on a replication job, where you set the source as backups, what are the requirements to have the job use an off-host backup proxy? When I set the job to use the backup as a source, the option to select an off-host backup proxy is greyed out, and the job uses on-host backup instead. Is there a specific requirement of OS or storage type for the Backup Repository? I cannot find anything in the documentation that says one way or another if off-host proxies are supported for replication from backup, and if it is supported what are the requirements to make it work.

Incase it matters, this is for Hyper-V, the hosts on both ends are Windows 2012 R2, the Veeam Server is 2008 R2 with locally attached storage for the backup repository.

[foggy]

Tim, with replication being performed from backup, Veeam B&R does not need to communicate with the source host and create a snapshot, the data is retrieved directly from the backup chain stored on the backup repository by the data mover agent installed on it. Hence no need to select the proxy.