[Vlive] Only downloads a single file when attempting to download a playlist

[kyuyeunk]

Checklist

• [x] I'm reporting a broken site support issue
• [x] I've verified that I'm running youtube-dlc version 2020.10.31
• [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 bug reports including closed ones
• [x] I've read bugs section in FAQ

Verbose log

[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['https://www.vlive.tv/video/113764/playlist/113852', '-v']
[debug] Loading archive file None
[debug] Encodings: locale UTF-8, fs utf-8, out utf-8, pref UTF-8
[debug] youtube-dlc version 2020.11.11-2
[debug] Git HEAD: d052b9a11
[debug] Python version 3.8.5 (CPython) - Linux-4.19.104-microsoft-standard-x86_64-with-glibc2.29
[debug] exe versions: ffmpeg 4.2.4, ffprobe 4.2.4
[debug] Proxy map: {}
[vlive:playlist] Downloading playlist 113852 - add --no-playlist to just download video
[vlive:playlist] 113852: Downloading webpage
[vlive:playlist] Downloading just video 113764 because no playlist was found
[vlive] 113764: Downloading webpage
[vlive] 113764: Downloading JSON metadata
[vlive] 113764: Downloading JSON metadata
[debug] Default format spec: bestvideo+bestaudio/best
[debug] Invoking downloader on 'http://globalv.video.p.rmcnmv.naver.com/c/read/v2/VOD_ALPHA/global_v_2019_02_19_407/c2da513a-340c-11e9-a5ac-246e963a49b9.mp4?_lsu_sa_=6365f6f311576da602df05ee6955d2bb2eeb3b486c08cfe13897a8c577283ba59e2c3a6464652b0d008531f2093e1b1ad6bfae5ec39e31da301c16889a1a1cb0139619e68e7367767c6c7343c68013d0'
[download] Destination: [V LIVE] 아이돌룸(IDOL ROOM) 39회 주Honey캠 - 이번주 픽돌 탄생 Jooheon's CAM - Birth of Today's PickDol-113764.mp4
[download] 100% of 8.28MiB in 00:02

Description

Attempting to download a playlist results in downloading a single video.

For example, link https://www.vlive.tv/video/113764/playlist/113852 contains total of 8 videos, but only downloads the video associated with the link, failing to download all videos within the playlist.

This behavior is simillar to adding --no-playlist option.

[blackjack4494]

223 should fix this @kyuyeunk maybe @SeonjaeHyeon can also contribute to that matter.