Metadata/playback issues with some reddit videos

[MomentofClarity]

• I've verified and I assure that I'm running youtube-dl 2019.04.07
• At least skimmed through the README, most notably the FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones
• Checked that provided video/audio/playlist URLs (if any) are alive and playable in a browser

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)

[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-v', u'https://www.reddit.com/r/aww/comments/ba7xrq/playing_the_shell_game_with_a_mountain_lion/']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2019.04.07
[debug] Python version 2.7.15rc1 (CPython) - Linux-4.15.0-47-generic-x86_64-with-neon-18.04-bionic
[debug] exe versions: ffmpeg 3.4.4, ffprobe 3.4.4, phantomjs 2.1.1, rtmpdump 2.4
[debug] Proxy map: {}
[RedditR] ba7xrq: Downloading JSON metadata
[Reddit] sdnt3d613pq21: Downloading m3u8 information
[Reddit] sdnt3d613pq21: Downloading MPD manifest
[debug] Default format spec: bestvideo+bestaudio/best
[debug] Invoking downloader on u'https://v.redd.it/sdnt3d613pq21/HLS_540_v4.m3u8'
[hlsnative] Downloading m3u8 manifest
[hlsnative] Total fragments: 6
[download] Destination: Playing the shell game with a mountain lion-sdnt3d613pq21.mp4
[download] 100% of 6.02MiB in 00:03
[debug] ffmpeg command line: ffprobe -show_streams 'file:Playing the shell game with a mountain lion-sdnt3d613pq21.mp4'

...
<end of log>

Description of your issue, suggested solution and other information

I've noticed two issues with some reddit videos today. It only happens to some of the videos, but I'm not sure what causes it to happen.

1) [Somewhat resolved, just FYI] When some videos are converted and then uploaded to a web server (on converted on the web server itself), and you have a link to the direct file, it does not play in any browser. Firefox gives "No video with supported format and MIME type found" and it just won't start playing in others.

Console output is

Media resource [video].mp4 could not be decoded, error: Error Code: NS_ERROR_DOM_MEDIA_METADATA_ERR (0x806e0006)
Details: static mozilla::MP4Metadata::ResultAndByteBuffer mozilla::MP4Metadata::Metadata(mozilla::ByteStream*): Cannot parse metadata

I was able to fix this by using the --add-metadata tag, and then it plays fine in browser, although this was not necessary before today.

Examples:

• https://www.reddit.com/r/aww/comments/ba7xrq/playing_the_shell_game_with_a_mountain_lion/
• https://www.reddit.com/r/MadeMeSmile/comments/ba7o36/sir_patrick_stewart_napping_with_his_new_foster/

2) [Main issue] Major rendering/playback issues with the first video between 6-8 seconds, 13-15 seconds, and 26-28 seconds. Happens on every browser and native video player I've tried. In MPV and Firefox it appears as a compression artifact (I think that's what it's called? not an expert on the topic..) and with VLC is just lags during that time.

• https://www.reddit.com/r/aww/comments/ba7xrq/playing_the_shell_game_with_a_mountain_lion/

^^ If you just run youtube-dl on that link you will see what I mean (hopefully), it happens on every computer I've tried.