Amazon is offering $4.99 Priority International Postage for items shipped and sold by Amazon US.
This is a faster postage method than the Expedited postage that they offer for free already for Prime members.
It means that anything ordered from the 5-10th of December which is the promo period should arrive in time for Christmas.
• The promotion is valid from 7:00 a.m. (AEST) 5th December to 7:00 a.m. (AEST) 10th December.
• This promotion entitles customers to receive discounted Priority International Delivery ($4.99 for Prime members and $9.99 for Non-Prime members) on all eligible items from Amazon US.
• The promotion is valid for a limited time only. Amazon reserves the right to cancel it at any time. Only items shipped and sold by Amazon US will be eligible for the offer when you checkout those items during the promotion period. If you do not purchase eligible items within the promotional period, you will not receive discounted priority delivery.
• The promotion applies only to eligible items shipped and sold by Amazon US. It does not apply to any products sold by other sellers (including third party sellers and Amazon AU). For example, if the promotion applies to cookware offered by Amazon US, the same cookware offered by other sellers on the Amazon.com.au website may not qualify.
• The discounted Priority International Delivery applies only to amazon.com.au members. It does not work on amazon.com.
In my understanding, US Prime membership has nothing to do with free or cheap international shipping to Australia - so it is irrelevant unless you want it for watching Prime videos of the US account.
Discounted or free shipping from the US is an offering by Australian Amazon Prime. Honestly, if they didn't offer it, it would be hard for them to scale their business here just based on the items listed on Aussie site and/ or US listed items with very high shipping charges.