I suspect that the 12 Mbps Network I/O and 0% Network Utilization values between the two tables are instantaneous --i.e., they display the values "right now"-- while the values within the columns with units of B/sec are actually "average B/sec over the past 60 seconds". You mentioned that the top-right graph also shows basically nothing from t-minus 42 seconds to zero time/"right now"; a 12 Mbps line on that graph would be basically indistinguishable from the x-axis and lines up with the instantaneous theory.
Further, the top-right graph has approximately 110 cells, and about 8 or 9 of those are filled (give or take). At that rate, the "average" Mbps for the past 60 seconds would be 1000 Mbps * (9 filled cells / 110 total cells) = 82 Mbps, or about 10 MBps, which approximately lines up with the given Total (B/sec) in the "Processes with Network Activity" table.
Finally, this link for Windows Server 2008 (I know that's not Windows 7, and I don't know if perfmon and Resource Monitor are the same thing) also indicates that the columns are over the entire minute:
The total bandwidth (in Bytes/min.) that is currently being sent and received by the application instance.
Granted, that link also says that the units are Bytes/min, but... that's the closest I found to documentation on something around Windows 7's age.
You could take more snapshots of the resource monitor with different conditions to see if my assumptions still hold.