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The crossdomain.xml file that is included in the www/delivery directory of Revive Adserver attempts to set the necessary cross domain settings required for video ad delivery.
Configuration Required
In the event that Revive Adserver has been installed so that it is available at the root of the URL path (i.e. Revive Adserver is installed at, for example, http://subdomain.domain.com/, and not at http://subdomain.domain.com/revive-adserver/), then no configuration will be required. Revive Adserver's root crossdomain.xml file will be able to be loaded (e.g. via http://subdomain.domain.com/crossdomain.xml) by Flash-based video players, which should set the required cross domain permitted-cross-domain-policies setting to "all", and therefore allow the delivery crossdomain.xml file to be loaded when video ad delivery is performed by Flash-based video players.
However, if Revive Adserver has not been installed in this way, you may find that Flash-based video players are not able to load video ads. If this is the case, copy Revive Adserver's root crossdomain.xml file to the root of your web server's home directory, so that Revive Adserver's root crossdomain.xml file will be able to be loaded (e.g. via http://subdomain.domain.com/crossdomain.xml).
This should resolve the issue of Flash-based video ads being unable to be loaded.