I've been trying for ages to get this bl00dy feature working
Every single initiation by either me or my contact fails to connect. We've tried all manner of settings, switched off/unloaded firewalls etc., but to no avail. Be interested to find out what, if anything, can be done to get it working.
2 Alternatives I've tried successfully are ICUII and CUSeeMe, both commercial applications but with trial periods. Though not free, they might be the best option if you know a) they work and b) you'll be talking/viewing frequently. (Both support webcams as well as voice.)
Good luck with Messenger!