A/V Functionality with Multi-User Screen Sharing

I've been trying to get a setup working on a 2011 Mac Mini Server (2 GHz i7, 16 GB RAM), wherein some audio/video routing and streaming takes place under a secondary user who is logged in through multi-user screen sharing. By 'secondary' I mean that User 1 is logged in at the physical console, while User 2 is only logged in through screen sharing. I've run into two issues:

1) Attempts to play video in VLC by User 2 throw the warning message, "OpenGL acceleration is not supported on your Mac", and the video is indeed pretty choppy and stuttery.

2) Audio is thus far impossible. User 2 doesn't have any volume slider. Changing default output in the Sound prefpane just changes the main default for the system (affects User 1). No sound plays or is seemingly routed at all for User 2, even when I tell VLC to output to Soundflower or WavTap devices, and then try to record from those devices under User 1 or 2. It's like sound doesn't even come out of the source programs for User 2.

So I'm looking for any suggestions on getting either working better for User 2. Are users not logged into the physical console just completely cut off from core A/V functionality? Is there any way to get OS X to be more equitable about this?

Thanks for any pointers.