VLC doesn't have a 'Save As...' style function to save the currently playing video, sorry. What it CAN do however is... a little different:

Record the currently playing video

Just like tape recorders of old, VLC offers functionality to 'record' whatever is currently playing to disk.

You have to enable Advanced Controls first. Go to View -> Advanced Controls. You will see these options appear:

Now, whenever you start playing a DVD or other media, you can simply hit the Record button to start and stop recording. The files are saved your Documents folder in .mpg format i.e.:

C:\Users\{username}\Videos\

Using this method you can save entire files, or just specific snippets. It's up to you. //

This is an example of downloading a youtube video via VLC command line options. The video is played very fast and can finish in seconds. The general format is:

vlc -vvv YOUTUBE_VIDEO_URL --sout file/ts:YOUR_FILE_NAME.mpg

Example:

vlc -vvv https://www.youtube.com/watch?v=K0hm-CebrzU --sout file/ts:yoram-ab.mpg

Details here: https://wiki.videolan.org/Documentation:Streaming_HowTo/Receive_and_Save_a_Stream/