Refreshing a VDB means :
1) will re-provision the VDB from the dSource. As with the normal provisioning process,
2) you can choose to refresh the VDB from a snapshot or a specific point in time.
Point 2 : REWIND right ? Please correct if i am wrong....
Hence REFRESH is doing the task of REWIND !!
Hence when you refresh a VDB, you are essentially re-setting it to the state you select during the refresh process.