Adobe Flash v10 will present the following message when a site wants to store info on your computer:
Adobe Flash Player Settings Local Storage s.ytimg.com is requesting permission to store information on your computer. Requested: up to 10 KB Currently Used: 4KB Allow/Deny
There are two way of changing settings.
Using the Local Settings Manager.
The Local Settings Manager supercedes the (“online”) Setting Manager mentioned below, but has limited controls.
It can found on Gentoo Linux at /opt/Adobe/flash-player32/bin/flash-player-properties (the xfce4 menu lists it at Applications -> Settings -> Adobe Flash Player).
However, it seems that you can only allow/deny all sites rather than set a global storage limit or alter settings on a per-site basis.
Using the “online” Settings Manager.
The “online” Settings Manager runs on the local machine but is displayed on the Adobe site.
The Global Storage Settings panel of this manager can be found at Adobe - Flash Player : Global Storage Settings panel.
Here you can set a default storage limit. I raised it to 100K to prevent most sites prompting me to allow/deny the storage space at the same time as preventing them storing whatever they want.
These settings won’t effect any sites that are already in your Flash history. You can increase the limits for those sites (or remove them from history) via the Website Storage Settings panel.
References: Adobe - Flash Player : Settings Manager