IANAIPL, but I don't think so. Sure, something like 'All comments posted are copyright by whoever posted them' might seem to be all well and good, but I doubt it would hold up in court, being that it's a public forum and all. Also, a copyright disclaimer could be interpreted as meaning that biggie.co.nz takes ownership of the comments, opening them (well, the domain name holder at least, unless there is a Biggie Limited), to legal liability for any defamatory comments. It would be a court battle to see what disclaimer is the 'more' legal one, the copyright or the one disclaiming liability at the bottom of each forum page.