Hi joshmvf,
From the error message you get it seems MG flash casinos need a microgaming-signed activeX plugin on top of the shockwave/flash player to run the games…
Virgin Casino uses the Wagerworks casino software, which is flash only (no download version available). Last year, following players feedback, Wagerworks upgraded the system to make it 100% compatible for Mac users.
The Casino is available for freeplay without registration, so I’d be curious to find out if you experience the same problem you have with MG.
If you get a chance could you possibly try to play a free game at Virgin Casino and let me know if that works under your current setup (Mac OS X + safari I expect)?
Let me know, cheers 