If I use a N1 headunit with N2 brain, how would I go about doing the video bypass??

black_sedan,

the same bypass would apply which would be grounding the light green wire.

This would only change if you upgrade to the latest map software (60mp) at which point you would have to perform the N1 Head Unit mod. Details of that mod are and have been listed. Search and you will find the N1 mod but be careful it requires taking the head unit apart and then extremely careful soldering attaching a very small wire to 2 points.

The N2 and N3 Head Unit are fairly simple to mod.

Hope this helps.

bcd1

Actually if you use any mapp software other than the 40 series that came with the n1 you'll have to do the solder bypass bcd1 is describing.