Recordings is not converted to mp4 when KMS is running as Docker container

I wanted to know that when KMS is running as Docker container and openmeetings is running in traditional way, i .e Extracting openmeetings archive.

How can 'nobody' user access '.webm' file from the Docker container and convert same into MP4 with ffmpeg installed on  host machine.

I have this question because in KMS docker container '.webm' is getting created but same 'mp4' file is not generated in host file system, which is practically correct because container is equivalent to light weight VM running on host and 'nobody' user doesn't have access to read file from container file system.

Please help me out with this as I can't access my recordings.