apache flex - How to use crossdomain.xml for my flash project...?

Question

This drives me crazy...I am trying to build a youtube player with flash and everytime I load a video, there is a runtime security sandbox error..I already put crossdomain.xml in my root server http://mysite.com but I am still getting the errors...Do I miss something? Do I have to load it into my flex project??Thanks for the reply...

My crossdomain.xml

<!-- <!DOCTYPE cross-domain-policy SYSTEM "http://www.macromedia.com/xml/dtds/cross-domain-policy.dtd">
    <cross-domain-policy>
       <allow-access-from domain="*.youtube.com"/>
        <allow-access-from domain="s.ytimg.com"/>
    </cross-domain-policy> 
 -->

Edit: 20100811T0723; this is the actual XML from http://popslinger.org/crossdomain.xml

<!DOCTYPE cross-domain-policy SYSTEM "http://www.macromedia.com/xml/dtds/cross-domain-    policy.dtd">
<cross-domain-policy>
<allow-access-from domain="*" />
</cross-domain-policy>

Answer 1

I get a lot of errors too but they generally seem to be on YouTube's side

Here's an example:

*** Security Sandbox Violation ***
SecurityDomain 'http://www.youtube.com/apiplayer?version=3' tried to access 
incompatible context 'http://s.ytimg.com/yt/swf/apiplayer3-vfl181412.swf'

As you can see, these are both YouTube domains

So I had a look at YouTube's own crossdomain policy files. It turns out that those files need to be updated. Read the following: http://www.adobe.com/devnet/flashplayer/articles/fplayer10_security_changes_02.html#head1

Here is the policy file from s.ytimg.com

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

which throws the following warning

Warning: Domain s.ytimg.com does not specify a meta-policy. Applying default meta-policy 'master-only'. This configuration is deprecated. See http://www.adobe.com/go/strict_policy_files to fix this problem.

and here's what it should look like

<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM
"http://www.adobe.com/xml/dtds/cross-domain-policy.dtd">

<cross-domain-policy>
<site-control permitted-cross-domain-policies="master-only"/>
<allow-access-from domain="*"/>
</cross-domain-policy>

Here's another warning:

Warning: Domain video-stats.video.google.com does not explicitly specify a meta-policy, but Content-Type of policy file http://video-stats.video.google.com/crossdomain.xml is 'text/x-cross-domain-policy'. Applying meta-policy 'by-content-type'.

It looks like YouTube should look into this, all these warnings and security error messages are pretty annoying.

Practically speaking, have a look at the errors, if your domain name doesn't appear anywhere, your crossdomain file is working fine.