Flash CS3 Tutorial
How to Blur Movie Symbol, Text or Button Using the Flash Blur Filter
You can use a blurred object to simulate motion or depth of field in your scene. Filter effects can be keyframed and faded over time using a motion tween.
Add a rectangular object to the workspace with the Rectangle tool (r key).
Select the rectangle and convert it to a Movie Symbol (Modify > Convert to Symbol (F8)).
With the rectangle Movie Symbol still selected, open the Filters panel by clicking the Filters tab (Window > Properties > Filters).
Add a filter to the Filter panel by clicking the plus (+) icon and selecting Blur from the pull-down menu.
In the dialog box you can set the Blur. By clicking the Lock icon next to Blur, you can adjust the x and y values independently.
Quality choices include Low, Medium, and High.