After installing VLC player the normal way, and subsequently trying to launch it, you may encounter a problem with gt4 causing VLC not to work properly. Basically nothing happens if you try to open VLC player normally, and there will be no error message indicating what is wrong.
The solution is to open a terminal and run VLC from the terminal, this will give you an error message similar to the below:
...skins2 interface error: no suitable dialogs provider found (hint: compile the qt4 plugin, and make sure it is loaded properly)...
This error hints that gt4 is not properly installed. You can try installing it by typing the following in a terminal:
sudo pacman -S qt4
Doing this should fix the problem, and allow you to finally use your favorite media player in Arch.