[ThePlatform] Only ads are downloaded

[rredford6]

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: ['--verbose', '--hls-prefer-native', '--cookies', 'cookies.txt', 'https://player.theplatform.com/p/HNK2IC/<snip>#playerurl=https%3A//www.nbc.com/the-profit/video/an-inside-look-kota-longboards/4117074']
[debug] Encodings: locale cp1252, fs mbcs, out cp437, pref cp1252
[debug] youtube-dl version 2020.06.06
[debug] Python version 3.4.4 (CPython) - Windows-10-10.0.17763
[debug] exe versions: ffmpeg N-91481-gb8c4d2b2ed, ffprobe N-91481-gb8c4d2b2ed
[debug] Proxy map: {}
[ThePlatform] 4117074: Downloading webpage
[ThePlatform] 4117074: Downloading SMIL data
[ThePlatform] 4117074: Downloading m3u8 information
[ThePlatform] 4117074: Downloading JSON metadata
[debug] Default format spec: bestvideo+bestaudio/best
[debug] Invoking downloader on 'https://west.manifest.na.theplatform.com/m/HNK2IC/<snip>'
[hlsnative] Downloading m3u8 manifest
[hlsnative] Total fragments: 381
[download] Destination: An Inside Look - KOTA Longboards-4117074.mp4
[download] 100% of 1.42GiB in 02:43
[debug] ffmpeg command line: ffprobe -show_streams "file:An Inside Look - KOTA Longboards-4117074.mp4"
[ffmpeg] Fixing malformed AAC bitstream in "An Inside Look - KOTA Longboards-4117074.mp4"
[debug] ffmpeg command line: ffmpeg -y -loglevel "repeat+info" -i "file:An Inside Look - KOTA Longboards-4117074.mp4" -c copy -f mp4 "-bsf:a" aac_adtstoasc "file:An Inside Look - KOTA Longboards-4117074.temp.mp4"

Description

Videos downloaded from The Platform are not downloading correctly.

I'm using an MSO that is not supported. Therefore I have to manually get the link to the embedded player manually by visiting the video page:

https://www.nbc.com/the-profit/video/an-inside-look-kota-longboards/4117074

And then running the following JavaScript command:

document.getElementsByTagName('iframe')[0].src

And then pass that in to youtube-dl (see verbose log above).

Then inspect the downloaded file:

ffprobe "An Inside Look - KOTA Longboards-4117074.mp4" | grep Duration
  Duration: 00:06:00.71, start: 0.000000, bitrate: 3962 kb/s

And then fetch the expected duration:

youtube-dl --get-duration <same url as above>
43:14

There seems to be 37 minutes missing. However upon playing back the video it is nothing but ads. Note that --include-ads was not specified. Nothing from the video got downloaded; all 43 minutes are missing

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If we manually inspect one of the m3u8 files listed in master.m3u8, we can see the following in there:

#EXT-X-VMAP-AD-BREAK:ID=mid_roll_3
<snip>
#EXT-X-VMAP-AD-BREAK-END

The lines between these comments need to be stripped before passing the data in to the downloader. Because right now the downloader is downloading them.

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This issue is reproducable on all videos from nbc.com that require login. Any video not requiring login downloads fine.