[nbcolympics:stream] Fix extractor

PR: https://github.com/ytdl-org/youtube-dl/pull/29688
Closes: #617, https://github.com/ytdl-org/youtube-dl/issues/29665

* Livestreams are untested
* If using ffmpeg as downloader, v4.3+ is needed since `-http_seekable` option is necessary
* Instead of making a seperate key for each arg that needs to be passed to ffmpeg, I made `_ffmpeg_args`
* This deprecates `_seekable`, but the option is kept for compatibility

Authored by: nchilada, pukkandan

yt_dlp/extractor/turner.py

@@ -144,7 +144,7 @@ class TurnerBaseIE(AdobePassIE):
                     m3u8_id=format_id or 'hls', fatal=False)
                 if '/secure/' in video_url and '?hdnea=' in video_url:
                     for f in m3u8_formats:
-                        f['_seekable'] = False
+                        f['_ffmpeg_args'] = ['-seekable', '0']
                 formats.extend(m3u8_formats)
             elif ext == 'f4m':
                 formats.extend(self._extract_f4m_formats(