Well somebody might come up with a scheme for using Gimp but IMHO
Not really a job for Gimp. The video you linked is only 13.3 seconds long but it is also 30 frames-per-second which in Gimp gives 399 layers to edit, individually to remove the green background. Add to that, the green is not uniform in colour (more later).
You can use a command line application ffmpeg and convert green to transparency (alpha mask)
where 0x00a300 is a green value from the video. That was about a mid-value green but still makes for noticable semi transparency. You need to experiment and try to get a better result. Output is a .mov because .mp4 does not support transparency.
To put that over the static background, use a simple video editor such as Openshot - looks like this. A final edit is a crop - that jpeg image is not a standard video frame size.
example https://i.imgur.com/44EP3Cj.mp4 and it still has the audio.
Not really a job for Gimp. The video you linked is only 13.3 seconds long but it is also 30 frames-per-second which in Gimp gives 399 layers to edit, individually to remove the green background. Add to that, the green is not uniform in colour (more later).
You can use a command line application ffmpeg and convert green to transparency (alpha mask)
Code:
ffmpeg -i B9MoCO8.mp4 -vf "chromakey=0x00a300:0.1:0.2" -c copy -c:v png output.movwhere 0x00a300 is a green value from the video. That was about a mid-value green but still makes for noticable semi transparency. You need to experiment and try to get a better result. Output is a .mov because .mp4 does not support transparency.
To put that over the static background, use a simple video editor such as Openshot - looks like this. A final edit is a crop - that jpeg image is not a standard video frame size.
example https://i.imgur.com/44EP3Cj.mp4 and it still has the audio.