brightcove subtitles broken

[claud9999]

Checklist

• I'm reporting a broken site support
• I've verified that I'm running youtube-dl version 2020.06.16.1
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar issues including closed ones

Verbose log

[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-v', u'--all-subs', u'https://www.metopera.org/link/8601ccf66b394032b83d5776cab34177.aspx?upc=811357019405']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2020.06.16.1
[debug] Python version 2.7.16 (CPython) - Darwin-18.7.0-x86_64-i386-64bit
[debug] exe versions: ffmpeg 4.2.2, ffprobe 4.2.2, rtmpdump 2.4
[debug] Proxy map: {}
[generic] 8601ccf66b394032b83d5776cab34177: Requesting header
[redirect] Following redirect to https://www.metopera.org/season/on-demand/opera/?upc=811357019405
[brightcove:met] None: Downloading webpage
[brightcove:met] 5524054113001: Downloading webpage
[brightcove:met] 5524054113001: Downloading webpage
[brightcove:new] 5524054113001: Downloading JSON metadata
[brightcove:new] 5524054113001: Downloading m3u8 information
[brightcove:new] 5524054113001: Downloading m3u8 information
[debug] Default format spec: bestvideo+bestaudio/best
[debug] Invoking downloader on u'https://hlsak-a.akamaihd.net/76009399001/5524254127001/76009399001_5524254127001_5524054113001.m3u8'
[download] La Traviata-5524054113001.mp4 has already been downloaded
[download] 100% of 3.79GiB
[debug] ffmpeg command line: ffprobe -show_streams 'file:La Traviata-5524054113001.mp4'
[ffmpeg] Fixing malformed AAC bitstream in "La Traviata-5524054113001.mp4"
[debug] ffmpeg command line: ffmpeg -y -loglevel 'repeat+info' -i 'file:La Traviata-5524054113001.mp4' -c copy -f mp4 '-bsf:a' aac_adtstoasc 'file:La Traviata-5524054113001.temp.mp4'

Description

Subtitle downloading is now inconsistent with brightcove sites. I've been downloading metopera.org free streams for a few weeks now (FYI I've paid for a year's subscription to support their work) and recently subtitles aren't being downloaded. Similar problems show up with sfopera.org free streams.

[dstftw]

youtube-dl have no brightcove:met extractor, no support for custom versions.