open bla.avi -a vlc works because OS X is using its Launch Services database to open the application VLC. This doesn't have anything to do with a command line binary of the same name, which isn't installed by default.
The binary you search for is in the
VLC.app package, so you can type that into a terminal:
/Applications/VLC.app/Contents/MacOS/VLC -I rc
This will open the interactive command line VLC. Or, execute the following in order to have the above line registered as an alias to
echo "alias vlc='/Applications/VLC.app/Contents/MacOS/VLC -I rc'" >> ~/.bash_profile
Once you've added this, you need to restart your Terminal. Now type
vlc and you'll get to the command line.
If you don't like the interactive interface or would like to use
VLC with other options, you need to edit your
~/.bash_profile accordingly, e.g. through
open -e ~/.bash_profile.