manually editing kodi playlists

Following up on the use of Kodi for theatre playouts - the previous posts below,
Work Stuff: optimizing kodi for planetarium projection

Work Stuff: playing custom local video playlist from Kodi

the playlists are located on the SDCARD and not on the USB drive containing the video files - 

Path to the video playlists is

STORAGE > .kodi/userdata/playlists/video

The editing has to be done as root, as no access otherwise.

Can't use UI, since gksudo is removed,

https://itsfoss.com/gksu-replacement-ubuntu/

and other methods also don't work,

https://github.com/linuxmint/nemo/issues/2929

The entries in the m3u files are of the form

#EXTINF:0,3002Fade-out Lights.avi

/var/media/NTFS500GB/CommonFiles/3002Fade-out Lights.avi

so we need to remember to edit the filename on two lines.