Prior to vlc 0.9.2 there was the section Subtitles-OSD -> Text renderer -> Font Effects and it was possible to choose Fat Outline.
Now in vlc 0.9.2 there is the new section Mac renderer and the Fat Outline it is disappeared.
I've erased the preferences, uninstalled the previous version of vlc, installed the 0.8.6e release but the default screen to screen 2 does not work yet on may iMac C2D with Leopard 10.5.2
I'm back to 0.8.6c and it works fine.
If it can help, I noticed that the vlc-0.8.6d-r22893-prerelease.dmg managed very well fullscreen on second display and there was not a blink when I swich from video in window and full screen.