How do I navigate to a samba location I've mounted in Nautilus on the command line?

In most cases:

$XDG_RUNTIME_DIR/gvfs

14.04:

/run/user/$(id -u)/gvfs

12.10:

/run/user/<username>/gvfs

12.04:

Since 12.04 the folder of mounted samba share is:

~/.cache/gvfs

11.10 and older

You can learn how to mount - it will sure works. But I think this is an easier solution for you: Nautilus mount smb partitions at ~/.gvfs (where ~/ means /home/user_name/ - example: /home/desgua/.gvfs).
You just have to navigate to there:

cd ~/.gvfs

Another option here, while not directly related to having mounted the directory in nautilus is to mount the location from the command line.

However, to mount samba volumes, you have to have CIFS support.

sudo apt-get install cifs-utils

From here, you have the option of where you want to mount the location. There are TWO "standards" of sorts for this. If you want the location to show up in the Places menu, you would mount it in /media. If not, you would mount it in /mnt (only to follow the common namespace for mounted volumes. There’s nothing wrong with mounting the directory in /home/$user/mount/someshare)

^{Illustration of the mounted location in the Places menu}

assuming that /media/myshare exist, you would achieve this by issuing the following command:

sudo mount -t cifs -o user=abc,password=def //xyz.220.131.233 /media/myshare

Side note

You can accomplish this automagically by appending the following string to your /etc/fstab configuration:

//xyz.220.131.233 /media/SambaMount cifs username=abc,password=def,rw,user,noauto 0 0

Notice the noauto flag, this will keep the volume from being mounted at boot, so when you're no longer at your workplace, it won't hang during boot trying to poll and mount that share.

in ubuntu 16.04 and vlc 2.2.2 ;

Select media > Open Directory and navigate to /run/user/1000/gvfs/ << ID number (1000) can be vary on your system.

Here you can see the shared folder name and select the folder whichever you want to add in playlist (see picture below)