[Feature Request] Name saved metadata JSON the same as the video file

[Deusdictum]

Is your feature request related to a problem? Please describe.
Currently the saved metadata JSON files have "metadata_[VIDEO_ID].json' format. It requires a lot of manual work to match those with the actual video files.

Describe the solution you'd like
JSON files should inherit the Filename format setting.
Also, would like to have an option to save in CSV format instead of JSON.