It seems that some information fields, which can be used much like (read-only) tag fields, are not documented on the English and German websites, anything relating to videos in particular:
I wonder whether that is intentional, because they only work for certain codecs (H.264 at least), but not for others (e.g. AV1, VP8 and VP9) which may be encountered in the wild (e.g. in YouTube rips). Since WebM support has been added in v3.01, this becomes more relevant because this format (which is a subset of Matroska / MKV) requires a Google VP video codec.