First of all, nice work. First impressions are good.
First bug I noticed - I tried Uninstalling the Soundpacks included, and then reinstalling them (I do things like this). A couple of times I've tried, and both times its crashed Messenger, meaning I have to start it back up.
Actually playing the sounds with another person hasn't been tested yet. I'm waiting for someone on my list to install the plug-in
A few other minor quibbles, but I'll try using it a bit more to get the feel of it. Just wanted to you know about the biggie I posted at the start.
Glad to finally see a beta tho. I'll be having fun with this one