**tl;dr**: Update `ffmpeg` ± `youtube-dl`.

Including the console output was helpful!

# Your inputs are only detected as 5 seconds long

    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'https://r1---sn-j5cax8pnpvo-x1xe6.googlevideo.com/videoplayback?keepalive=yes&source=yt_live_broadcast&pl=24&itag=136&mime=video%2Fmp4&expire=1521354001&c=WEB&sparams=aitags%2Ccmbypass%2Cei%2Cgcr%2Cgir%2Chang%2Cid%2Cip%2Cipbits%2Citag%2Ckeepalive%2Clive%2Cmime%2Cmm%2Cmn%2Cms%2Cmv%2Cnoclen%2Cpl%2Crequiressl%2Csource%2Cexpire&aitags=133%2C134%2C135%2C136%2C160&signature=727E04BDE2851159A8A9327CDBAB503BBDC37267.2168845A24D2FFD5496AA2F5D2D6AACA59BB69D2&cmbypass=yes&ipbits=0&hang=1&beids=%5B9466592%5D&ms=lv&mt=1521331971&mv=u&live=1&key=yt6&ip=152.168.37.75&id=0R0T0mQmx7I.0&gir=yes&mm=32&mn=sn-j5cax8pnpvo-x1xe6&ei=sbCtWvOcLJTWxAS644e4Ag&noclen=1&gcr=ar&requiressl=yes&ratebypass=yes':
      Metadata:
    ...
       Duration: 00:00:05.00, start: 0.000000, bitrate: 2419 kb/s
    
    Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'https://r1---sn-j5cax8pnpvo-x1xe6.googlevideo.com/videoplayback?ip=152.168.37.75&mm=32&mn=sn-j5cax8pnpvo-x1xe6&expire=1521354004&pl=24&gir=yes&signature=16F13864FDF56FFDF2E08B248355CD1257D2E4FF.C7DBD2A865733005704660CD0EA82A90EFCFC03D&id=0R0T0mQmx7I.0&mt=1521331971&mv=u&ms=lv&hang=1&ipbits=0&itag=140&gcr=ar&requiressl=yes&source=yt_live_broadcast&keepalive=yes&ei=s7CtWsq0Ko7UxQT__pSgBA&noclen=1&sparams=cmbypass%2Ccompress%2Cei%2Cgcr%2Cgir%2Chang%2Cid%2Cip%2Cipbits%2Citag%2Ckeepalive%2Clive%2Cmime%2Cmm%2Cmn%2Cms%2Cmv%2Cnoclen%2Cpl%2Crequiressl%2Csource%2Cexpire&cmbypass=yes&compress=yes&key=yt6&mime=audio%2Fmp4&c=WEB&live=1&ratebypass=yes':
      Metadata:
       ...
      Duration: 00:00:04.99, start: 0.000000, bitrate: 130 kb/s

# Your `ffmpeg` version is quite old

> `ffmpeg version 2.8.11-0ubuntu0.16.04.1 Copyright (c) 2000-2017 the FFmpeg developers`

2.8 dates from around early 2016, from what I can tell. You are strongly suggested to update to the latest `ffmpeg`; preferably the latest `git HEAD`, but otherwise [this PPA might be of use](https://launchpad.net/~jonathonf/+archive/ubuntu/ffmpeg-3) for Ubuntu.

# Update your `youtube-dl` version as well

I get quite a different output from you for the same URL:

    $ youtube-dl --list-formats https://www.youtube.com/watch?v=0R0T0mQmx7I
    [youtube] 0R0T0mQmx7I: Downloading webpage
    [youtube] 0R0T0mQmx7I: Downloading video info webpage
    [youtube] 0R0T0mQmx7I: Extracting video information
    [youtube] 0R0T0mQmx7I: Downloading m3u8 information
    [youtube] 0R0T0mQmx7I: Downloading MPD manifest
    [info] Available formats for 0R0T0mQmx7I:
    format code  extension  resolution note
    91           mp4        256x144    HLS  197k , avc1.42c00b, 30.0fps, mp4a.40.5@ 48k
    92           mp4        426x240    HLS  338k , avc1.4d4015, 30.0fps, mp4a.40.5@ 48k
    93           mp4        640x360    HLS  829k , avc1.4d401e, 30.0fps, mp4a.40.2@128k
    94           mp4        854x480    HLS 1380k , avc1.4d401f, 30.0fps, mp4a.40.2@128k
    95           mp4        1280x720   HLS 2593k , avc1.4d401f, 30.0fps, mp4a.40.2@256k (best)
    $ youtube-dl --version
    2018.03.14

# With a recent `ffmpeg` and `youtube-dl` version, you get the expected result:

    $ ffmpeg -i $(youtube-dl -f 91 -g  https://www.youtube.com/watch?v=0R0T0mQmx7I) \
    -i $(youtube-dl -f 95 -g https://www.youtube.com/watch?v=0R0T0mQmx7I) \
    -c:v copy -c:a aac -strict experimental -t 00:02:00 output.mp4
    
    (...)
    
    $ ffprobe output.mp4
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output.mp4':
      Metadata:
        major_brand     : isom
        minor_version   : 512
        compatible_brands: isomiso2avc1mp41
        encoder         : Lavf57.83.100
      Duration: 00:02:00.02, start: 0.000000, bitrate: 1784 kb/s
        Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv,     bt709), 1280x720 [SAR 1:1 DAR 16:9], 1648kb/s, 30 fps, 30 tbr, 90k tbn, 60 tbc (default)
        Metadata:
          handler_name    : VideoHandler
        Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 129 kb/s (default)
        Metadata:
          handler_name    : SoundHandler

[Full output from `ffmpeg` invocation](http://ix.io/YVd).