What wires in the m12 connector for the SV 120 camera do you use to connect to the MD5-8

You can find the wiring of the M12 connector in the IQAN-SV instruction book, it is wired according to standard ethernet M12 D coded connector:

For connecting to MD5 ethernet port 2 - which is typically used for cameras:

C1:18  Ethernet 2 TD+ (not available on MD5-5)
C1:19  Ethernet 2 RD+ (not available on MD5-5)

C1:4    Ethernet 2 TD- (not available on MD5-5)
C1:5    Ethernet 2 RD- (not available on MD5-5)

For connecting to MD5 ethernet port 1 - eg. on MD5-5 or for a second camera without ethernet switch:

C1:15  Ethernet 1 TD+
C1:16  Ethernet 1 RD+

C1:1    Ethernet 1 TD-

C1:2    Ethernet 1 RD-