How to play this files? I tried with VLC and Totem and Kaffein but nothing. Blank screen.

I routinely play flv files with vlc, and xine-ui, and smplayer. xine-ui uses the same video engine (libxine1) as kaffeine.

Ensure you have installed Packman repository into your software package manager, and install w32codec-all, and the packman packaged libxine1 (and not the Novell/SuSE-GmbH packaged xine-lib). Also install the Packman (and not videolan) packaged vlc. I also pefer the packman packaged kaffeine over the Novell/SuSE-GmbH packaged kaffeine.

Make sure ffmpeg and libffmpeg are installed from the packman repository

Do you have compiz enabled. If yes, then open VLC, goto Settings->Preferences and check the Advanced options checkbox at botton of the settings window. Now expand Video from left column and click on output modules. In the drop menu on right side, select X11 video output. Click Save button and restart VLC. Check now with the FLV files.