Using mencoder to record a video

I'm trying to use mencoder to record a video. The following command was taken from an [online tutorial](https://wiki.archlinux.org/index.php/Webcam_setup#MPlayer) : mencoder tv:// -tv driver=v4l2:width=640:height=480:device=/dev/video0:forceaudio:adevice=/dev/dsp -ovc lavc -oac mp3lame -lameopts cbr:br=64:mode=3 -o filename.avi The output is as follows: MEncoder SVN-r37379 (C) 2000-2015 MPlayer Team 210 audio & 441 video codecs success: format: 9 data: 0x0 - 0x0 TV file format detected. Selected driver: v4l2 name: Video 4 Linux 2 input author: Martin Olschewski comment: first try, more to come ;-) v4l2: your device driver does not support VIDIOC_G_STD ioctl, VIDIOC_G_PARM was used instead. Selected device: UVC Camera (046d:0825) Capabilities: video capture streaming supported norms: inputs: 0 = Camera 1; Current input: 0 Current format: YUYV tv.c: norm_from_string(pal): Bogus norm parameter, setting default. v4l2: ioctl enum norm failed: Inappropriate ioctl for device Error: Cannot set norm! Selected input hasn't got a tuner! Unable to open '/dev/dsp': No such file or directory Unable to open '/dev/dsp': No such file or directory Unable to open '/dev/dsp': No such file or directory v4l2: ioctl set mute failed: Invalid argument v4l2: 0 frames successfully processed, 0 frames dropped. ============ Sorry, this file format is not recognized/supported ============= === If this file is an AVI, ASF or MPEG stream, please contact the author! === Cannot open demuxer. Exiting... user@ArchBox:~/Dropbox$ mencoder tv:// -tv driver=v4l2:width=640:height=480:device=/dev/video0:forceaudio:ade[15838:17998:0117/045341:ERROR:cert_verify_proc_nss.cc(922)] CERT_PKIXVerifyCert for api.tldr.io failed err=-8181 How do I address these errors?