I'm a Canadian contributor who received a notice that my form had expired.  The new form is much more complicated than the old one (actually, just much longer -- most of it doesn't apply).   I found this page to be a very useful guide on what to fill out:

http://ontariotaxmen.ca/w8-ben-e.htm

If you don't fill out this horrible form, US tax will be deducted from your revenue even though you live in a tax treaty country that exempts you from US tax.

You can still get it back by filing a US tax return as a non-resident alien. Though that would most likely require getting a ITIN first, if you don't have it or SSN yet.