@frenchfrog
Did you try with CFW to get solve nfs and black screen problem?
As I know substitute not apply when external player is use.
Anyway as I remember with last 3-4 version of OFW Kodi don't have permission to access /mnt/nfsShare or /mnt/smb.
Thanks @pcristi for your reply.
I uploaded the firmware v2.1.4 which I guess is the latest available one. For kodi, I had no problem to declare my mounted nfsShare as a source. You cannot browse /mnt/nfsShare or /mnt/smb folders but if you enter directly the correct path (a subfolder like /mnt/nfsShare/nfs_share1/), you can see its content.
My solution would be that the himedia wrapper allows substitutions if needed. It seems a possible feature of the XBMC/Kodi Wrapper available in the play store.
I would like in my case to test if it is working by doing the following:
Replace URL From 1: (?i)nfs://192.168.8.90/volume1/video/movie/
Replace URL To 1: file:///mnt/nfsShare/nfs_share1/movie/
It should do the job in that case. By the way, I just noticed that I didn't started my substituted string by "file://" in my advancedsettings.xml file. I will have to check if it changes something (I am not at home right now to perform this check).