In scenarios where Media Gallery is not needed, it can be disabled using TaskPaneSettings >> MediaGallery >> Enabled property. When Media Gallery is disabled, the Media Gallery command in main toolbar will also be removed.
The media retrieved as results of media search action will be displayed as thumbnails in media result container. By default, the thumbnail size is set to 55x55px size. To modify the size of thumbnail, the following properties can be configured: TaskPaneSettings >> MediaGallery >> ImageHeight and TaskPaneSettings >> MediaGallery >> ImageWidth.
When media search action is performed in multiple media resources, it could result in a large number of media. Retrieving large number of media could affect the performance when rendering and interacting with elements in client-side, thus by design the result is limited to 100 media only. To specify a larger number of search results, simply modify the value in TaskPaneSettings >> MediaGallery >> MaxMediaRetrieved property.
When first opened, media search action will be automatically performed in Media Gallery pane. This behavior can be disabled by setting TaskPaneSettings >> MediaGallery >> SearchMediaOnLoad property to False.