Can't download and emerge subtitle from Youtube

[KwToPA]

proxychains4 youtube-dl -v --embed-subs https://www.youtube.com/watch?v=QV9x79_WYbk
[proxychains] config file found: /usr/local/Cellar/proxychains-ng/4.7/etc/proxychains.conf
[proxychains] preloading /usr/local/Cellar/proxychains-ng/4.7/lib/libproxychains4.dylib
[proxychains] DLL init
[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'-v', u'--embed-subs', u'https://www.youtube.com/watch?v=QV9x79_WYbk']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2016.10.07
[proxychains] DLL init
[debug] Python version 2.7.9 - Darwin-14.5.0-x86_64-i386-64bit
[debug] exe versions: ffmpeg 3.0.1-tessus
[debug] Proxy map: {}
[youtube] QV9x79_WYbk: Downloading webpage
[proxychains] Strict chain  ...  127.0.0.1:1080  ...  www.youtube.com:443  ...  OK
[youtube] QV9x79_WYbk: Downloading video info webpage
[proxychains] Strict chain  ...  127.0.0.1:1080  ...  www.youtube.com:443  ...  OK
[youtube] QV9x79_WYbk: Extracting video information
[youtube] QV9x79_WYbk: Downloading MPD manifest
[proxychains] Strict chain  ...  127.0.0.1:1080  ...  manifest.googlevideo.com:443  ...  OK
WARNING: Requested formats are incompatible for merge and will be merged into mkv.
[debug] Invoking downloader on u'https://r2---sn-ogueln7y.googlevideo.com/videoplayback?id=415f71efdfd661b9&itag=137&source=youtube&requiressl=yes&mn=sn-ogueln7y&initcwndbps=7168750&nh=IgpwcjAzLm5ydDE5KgkxMjcuMC4wLjE&pl=23&ms=au&mm=31&mv=m&ratebypass=yes&mime=video/mp4&gir=yes&clen=440262187&lmt=1429506821565040&dur=1391.473&key=dg_yt0&signature=1DE7B57A6022731F59040FD5227E2E2F265353B0.172E846884E753999FAEF7984A9FCD64347CC05D&upn=fOYlPU-BxkU&mt=1476024685&ip=104.238.160.192&ipbits=0&expire=1476046985&sparams=ip,ipbits,expire,id,itag,source,requiressl,mn,initcwndbps,nh,pl,ms,mm,mv,ratebypass,mime,gir,clen,lmt,dur'
[proxychains] Strict chain  ...  127.0.0.1:1080  ...  r2---sn-ogueln7y.googlevideo.com:443  ...  OK
[download] Destination: You Don't Know Shit - VICE Reports (Full Length)-QV9x79_WYbk.f137.mp4
[download] 100% of 419.87MiB in 06:16
[debug] Invoking downloader on u'https://r2---sn-ogueln7y.googlevideo.com/videoplayback?id=415f71efdfd661b9&itag=251&source=youtube&requiressl=yes&mn=sn-ogueln7y&initcwndbps=7168750&nh=IgpwcjAzLm5ydDE5KgkxMjcuMC4wLjE&pl=23&ms=au&mm=31&mv=m&ratebypass=yes&mime=audio/webm&gir=yes&clen=19341948&lmt=1449573100149750&dur=1391.481&key=dg_yt0&signature=3C6D8B70E732A25B836BF4E1238982E102A9FE0A.8E545446065094C0F52A7A4AE47A45DAC44E80F5&upn=fOYlPU-BxkU&mt=1476024685&ip=104.238.160.192&ipbits=0&expire=1476046985&sparams=ip,ipbits,expire,id,itag,source,requiressl,mn,initcwndbps,nh,pl,ms,mm,mv,ratebypass,mime,gir,clen,lmt,dur'
[proxychains] Strict chain  ...  127.0.0.1:1080  ...  r2---sn-ogueln7y.googlevideo.com:443  ...  OK
[download] Destination: You Don't Know Shit - VICE Reports (Full Length)-QV9x79_WYbk.f251.webm
[download] 100% of 18.45MiB in 00:16
[ffmpeg] Merging formats into "You Don't Know Shit - VICE Reports (Full Length)-QV9x79_WYbk.mkv"
[debug] ffmpeg command line: ffmpeg -y -i 'file:You Don'"'"'t Know Shit - VICE Reports (Full Length)-QV9x79_WYbk.f137.mp4' -i 'file:You Don'"'"'t Know Shit - VICE Reports (Full Length)-QV9x79_WYbk.f251.webm' -c copy -map 0:v:0 -map 1:a:0 'file:You Don'"'"'t Know Shit - VICE Reports (Full Length)-QV9x79_WYbk.temp.mkv'
Deleting original file You Don't Know Shit - VICE Reports (Full Length)-QV9x79_WYbk.f137.mp4 (pass -k to keep)
Deleting original file You Don't Know Shit - VICE Reports (Full Length)-QV9x79_WYbk.f251.webm (pass -k to keep)
[ffmpeg] There aren't any subtitles to embed

[dstftw]

You must use --write-sub.