Volumetric videos can be rendered to a few different formats, each has their own characteristics and requirements.
You can identify the video format by the file name, each ends with the text _TouchlyN, with N being the format identifier.
For example: video_Touchly0.mp4
Do not change this ending or it won't be correctly detected.
You can use you own method for creating videos as long as you follow the same Image layout and naming conventions. This is useful for example for making 3D rendered content.