Downloads from Reddit result in video with artifacts not present in source

[ghost]

Checklist

• [ x ] I'm reporting a broken site support
• [ x ] I've verified that I'm running youtube-dl version 2019.05.20
• [ x ] I've checked that all provided URLs are alive and playable in a browser
• [ x ] I've checked that all URLs and arguments with special characters are properly quoted or escaped
• [ x ] I've searched the bugtracker for similar issues including closed ones

Verbose log

$ ./youtube-dl -v "https://www.reddit.com/r/PublicFreakout/comments/bulu4s/this_man_is_literally_on_fire/"
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', 'https://www.reddit.com/r/PublicFreakout/comments/bulu4s/this_man_is_literally_on_fire/']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2019.05.20
[debug] Python version 3.7.3 (CPython) - Linux-5.1.0-rc6-x86_64-with-arch-Arch-Linux
[debug] exe versions: ffmpeg 4.1.3, ffprobe 4.1.3, rtmpdump 2.4
[debug] Proxy map: {}
[RedditR] bulu4s: Downloading JSON metadata
[Reddit] ri48ogn3o7131: Downloading m3u8 information
[Reddit] ri48ogn3o7131: Downloading MPD manifest
[debug] Default format spec: bestvideo+bestaudio/best
[debug] Invoking downloader on 'https://v.redd.it/ri48ogn3o7131/HLS_360_v4.m3u8'
[hlsnative] Downloading m3u8 manifest
[hlsnative] Total fragments: 15
[download] Destination: This man is literally on fire-ri48ogn3o7131.fhls-1385.mp4
[download] 100% of 9.78MiB in 00:04
[debug] Invoking downloader on 'https://v.redd.it/ri48ogn3o7131/audio'
[download] Destination: This man is literally on fire-ri48ogn3o7131.fdash-AUDIO-1.m4a
[download] 100% of 1.26MiB in 00:01
[ffmpeg] Merging formats into "This man is literally on fire-ri48ogn3o7131.mp4"
[debug] ffmpeg command line: ffmpeg -y -loglevel repeat+info -i 'file:This man is literally on fire-ri48ogn3o7131.fhls-1385.mp4' -i 'file:This man is literally on fire-ri48ogn3o7131.fdash-AUDIO-1.m4a' -c copy -map 0:v:0 -map 1:a:0 'file:This man is literally on fire-ri48ogn3o7131.temp.mp4'
Deleting original file This man is literally on fire-ri48ogn3o7131.fhls-1385.mp4 (pass -k to keep)
Deleting original file This man is literally on fire-ri48ogn3o7131.fdash-AUDIO-1.m4a (pass -k to keep)

Description

Downloaded videos from Reddit result in severe artifacts not present in the source video. Seems to happen about every 6 seconds.

It is the same bug report as this #21034 except it was closed as duplicate without any mention of the actual duplicate issue.

I believe this original bug report was probably mistakenly closed.

[ghost]

@dstftw Please tell us what issue this is a duplicate of.