I don't believe Microsoft's port of Microsoft Messenger for Mac has video capabilities, but
aMSN does.
I was also shocked that Messenger for Mac doesn't have video support (or offline messages!). I ended up sticking with it, even though it sucks.
I tried out aMSN, and couldn't believe how crap it ran. Why does it take a good 2 seconds before it starts scrolling through my contact list? For an open source project, I was EXTREMELY disappointed, specially given that aMSN for Windows works great!
I tried Adium, and although it works great, I was turned off by the fact that it didn't sync with my Hotmail e-mail (ie, telling me when I had new mail). Actually, thinking about it now, Messenger for Mac's synchronization with my Hotmail account is also crap, so I might just pick up Adium again!