The « grouped media resource » report displays a flat report which includes both the domain and the path to the media resource, whereas the regular « media resource » report displays a hierarchical view of your media resources by domain. In the grouped resource report, any file extensions (such as mp4 and mov) and any URL query parameters are removed. This is useful if you offer your videos or audio in different formats, as the report will give you a clean aggregated view of a single media resource.

Previous FAQ: Will the reports be shown in the Matomo Mobile app for Android and iOS?