If you can post a couple of screenshots it will help
1. Gimp showing the tools and tool settings / layer(s) dock along with the image & painted in mask.
2. The gmic settings and options.
The main issues for not getting a result is as mentioned earlier.
The mask colour not the same as painted in the image and defined in gmic. That was dealt with in the video by colour picking the mask colour from within gmic. That will result in a zip-though and no result. Probably the problem.
The input layer as used by gmic. Active is default and if there is only one layer then there is no ambiguity.
The image size. A large image does cause problems. That can be alleviated by a selection larger than the mask area. G'mic does require surrounding pixels to 'paint into' the mask area. Areas of transparency can cause problems.
Finally, the mask does need a hard edge, anti-aliasing results in a coloured border.
1. Gimp showing the tools and tool settings / layer(s) dock along with the image & painted in mask.
2. The gmic settings and options.
The main issues for not getting a result is as mentioned earlier.
The mask colour not the same as painted in the image and defined in gmic. That was dealt with in the video by colour picking the mask colour from within gmic. That will result in a zip-though and no result. Probably the problem.
The input layer as used by gmic. Active is default and if there is only one layer then there is no ambiguity.
The image size. A large image does cause problems. That can be alleviated by a selection larger than the mask area. G'mic does require surrounding pixels to 'paint into' the mask area. Areas of transparency can cause problems.
Finally, the mask does need a hard edge, anti-aliasing results in a coloured border.