VLC 2.1.5 (all versions and 2.2.0) plays only audio not video My 27" iMac on Yosemite, presents the same symptoms described in  'VLC in Mac does not show video window 2'. I tried all the actions available ie reinstalling, trashing preferences, the solutions proposed in the above mentioned questions etc but the result is the same: for all formats on file open or on double click, the application opens a new video window who closes immediately and the clip plays only the audio track.
The same clips play OK on QT, RealPlayer, MPlayer etc.
I've experienced something similar with VLC. Typically, I play vids in full screen on my second display connected to my MacBook. When I am not connected to the external display and I play a vid, VLC seems to want to still play in this dual display mode. So it's like it's playing on a ghost second display.

If this is your situation, the easiest solution is to simply press 'Escape'. That pulls the vid out of full screen mode (on the ghost second monitor) and displays it in windowed mode.

From there you should be good.

(P.S. I just wrote this same thing in another similar VLC post earlier today... Must be something in the air.)