TYPO3 Core

\TYPO3\CMS\Backend\Form\Container\InlineControlContainer
dependency between $allowed and $onlineMediaAllowed makes it impossible to create a button for "Add Media by URL" button only. You can't create this button without creating the "Select & Upload Files" Button.

Starting from Line 478
if (
       $folder instanceof Folder
        && $folder->checkActionPermission('add')
        ) {
        // Create "Select & Upload Files" Button
        if (!empty($onlineMediaAllowed)) {
            // Create "Add Media by URL" Button
        }
}

I suggest to seperate those both if querries.