Unfortunately, the claimed videos are in some tests in youtube_dl/extractor/youtube.py, e.g.

        # JS player signature function name containing $
        {
            'url': 'https://www.youtube.com/watch?v=nfWlot6h_JM',
            'info_dict': {
                'id': 'nfWlot6h_JM',
                'ext': 'm4a',
                'title': 'Taylor Swift - Shake It Off',
                'description': 'md5:307195cd21ff7fa352270fe884570ef0',
                'duration': 242,
                'uploader': 'TaylorSwiftVEVO',
                'uploader_id': 'TaylorSwiftVEVO',
                'upload_date': '20140818',
            },
            'params': {
                'youtube_include_dash_manifest': True,
                'format': '141/bestaudio[ext=m4a]',
            },
        },