Repository: yt-dlp/yt-dlp
File: yt_dlp/extractor/brilliantpala.py (Python)

Code before:

        if self._html_search_regex(
            r'(?P<warning>Your username / email and password)', logged_page,
                'authentication failure warning', group='warning', fatal=False, default=''):
            raise ExtractorError('wrong username or password', expected=True)

        if self._html_search_regex(
            r'(?P<button_text>Logout Other Devices)', logged_page, 'logout device button',
                group='button_text', fatal=False, default=''):
            logout_device_form = self._hidden_inputs(logged_page)
            self._download_webpage(
                self._LOGOUT_DEVICES_API, None, headers={'Referer': self._LOGIN_API},
                note='Logging out other devices', data=urlencode_postdata(logout_device_form))

    def _real_extract(self, url):
        course_id, content_id = self._match_valid_url(url).group('course_id', 'content_id')
        video_id = f'{course_id}-{content_id}'

        username = self._get_logged_in_username(self._download_webpage(url, video_id))

        content_json = self._download_json(
            self._CONTENT_API.format(content_id=content_id), video_id,
            note='Fetching content info', errnote='Unable to fetch content info')

        entries = []
        for stream in traverse_obj(content_json, ('video', 'streams')):
            formats = self._extract_m3u8_formats(
                m3u8_url=stream['url'], video_id=video_id)
            for format in formats:
                format['hls_aes'] = {
                    'uri': self._HLS_AES_URI.format(content_id=content_id)}
            entry = {
                'id': str(stream['id']),
                'title': dict_get(content_json, 'title', ''),
                'formats': formats,
                'http_headers': {'X-Key': hashlib.sha256(username.encode('ascii')).hexdigest()},
                'thumbnail': content_json.get('cover_image'),
                'live_status': 'not_live',
            }
            entries.append(entry)

        return self.playlist_result(
            entries, playlist_id=video_id, playlist_title=content_json.get('title'))


class BrilliantpalaElearnIE(BrilliantpalaIE):
    IE_NAME = 'Brilliantpala:Elearn'
    IE_DESC = 'VoD on elearn.brilliantpala.org'
    _VALID_URL = r'https?://elearn\.brilliantpala\.org/courses/(?P<course_id>\d+)/contents/(?P<content_id>\d+)/?'
    _TESTS = [{
        'url': 'https://elearn.brilliantpala.org/courses/42/contents/12345/',

Review comment (suggestion):
Branching will guarantee a list, and filtering can guarantee dicts with useful values
```suggestion
        for stream in traverse_obj(content_json, ('video', 'streams', lambda _, v: v['id'] and v['url'])):
```

Code after:

        if self._html_search_regex(
                r'(Your username / email and password)', logged_page, 'auth fail', default=None):
            raise ExtractorError('wrong username or password', expected=True)

        # the maximum number of logins is one
        if self._html_search_regex(
                r'(Logout Other Devices)', logged_page, 'logout devices button', default=None):
            logout_device_form = self._hidden_inputs(logged_page)
            self._download_webpage(
                self._LOGOUT_DEVICES_API, None, headers={'Referer': self._LOGIN_API},
                note='Logging out other devices', data=urlencode_postdata(logout_device_form))

    def _real_extract(self, url):
        course_id, content_id = self._match_valid_url(url).group('course_id', 'content_id')
        video_id = f'{course_id}-{content_id}'

        username = self._get_logged_in_username(url, video_id)

        content_json = self._download_json(
            self._CONTENT_API.format(content_id=content_id), video_id,
            note='Fetching content info', errnote='Unable to fetch content info')

        entries = []
        for stream in traverse_obj(content_json, ('video', 'streams', lambda _, v: v['id'] and v['url'])):
            formats = self._extract_m3u8_formats(stream['url'], video_id, fatal=False)
            if not formats:
                continue
            entries.append({
                'id': str(stream['id']),
                'title': content_json.get('title'),
                'formats': formats,
                'hls_aes': {'uri': self._HLS_AES_URI.format(content_id=content_id)},
                'http_headers': {'X-Key': hashlib.sha256(username.encode('ascii')).hexdigest()},
                'thumbnail': content_json.get('cover_image'),
            })

        return self.playlist_result(
            entries, playlist_id=video_id, playlist_title=content_json.get('title'))


class BrilliantpalaElearnIE(BrilliantpalaBaseIE):
    IE_NAME = 'Brilliantpala:Elearn'
    IE_DESC = 'VoD on elearn.brilliantpala.org'
    _VALID_URL = r'https?://elearn\.brilliantpala\.org/courses/(?P<course_id>\d+)/contents/(?P<content_id>\d+)/?'
    _TESTS = [{
        'url': 'https://elearn.brilliantpala.org/courses/42/contents/12345/',
        'only_matching': True,
    }, {
        'url': 'https://elearn.brilliantpala.org/courses/98/contents/36683/',
        'info_dict': {