To access these files from a SWF file hosted on another domain

Extract from Chapter 9 P182, Creating Mashups with Adobe Flex and AIR, friends of ED
To access these files from a SWF file hosted on another domain, you need to set up a crossdomain.xml file within your bucket:

<cross-domain-policy>
 <allow-access-from domain="*" />
</cross-domain-policy>

To prevent access from certain domains, you can restrict your list of allowed domains as necessary from within the crossdomain.xml file:

<cross-domain-policy>
 <allow-access-from domain="*.mydomain.com" />
</cross-domain-policy>