• Open Flash 8.0. Select New/Flash Document.
• Import the image you would like to blur by clicking on File/Import to Stage and select the image.
• Select the image on the stage and choose Modify/Convert To Symbol. Name the symbol blur and choose Movie Clip as Type.

Step 2: Create the blur effect

• Select the blur symbol on the stage.
• In the Properties Inspector, choose the Filters tab
• Click on the '+' icon and choose Blur.
• Choose 100 for Blur X and Blur Y and Quality as Medium.
  

Step 3: Create the animation

• In the timeline window right click on the 50th frame choose insert keyframe. Select the movie clip and change the blur filter X and Y values to 0 to remove the blur effect.
• Select any frame between Frames 1 and 50 and select Motion from the tween pop-up menu in the Property inspector.
• Press Ctrl+S to save your changes.

Press Ctrl+Enter to view your animation.

You can also blur only the X coordinates by removing the lock icon in the filters inspector and changing Blur X to 100 and Blur Y to 0. The effect can be seen below. You can try different blur effects by simply adjusting the blur X and blur Y values.