Directly connected via 21 pin scart to scart lead from the source (DVR) scart output to the VCR scart input.
Now this VCR scart socket must be selected using the VCR remote control unit in order to record from the source and usually involves selecting the A.V button. Some videos have more than one socket and can be AV1, AV2 or even AV3 if front sockets are fitted. Older videos with 1 scart socket and no A.V button may be channel 0 on the remote.
Tony
December 2006