Best Way to Avoid Blurry Videos

One method that has worked for me to improve the video quality within published slides is the following:

1.  Determine the resolution of the screen you used to record the video.  For example, my monitor is 1920 x 1080.  

2.  Choose the higher of the two dimensions (e.g., 1920).  Set your story size using that dimension and a corresponding dimension that maintains a 4:3 ratio.  For example, I've set my story size to 1920 x 1440.  Choose the option to lock the aspect ratio.

3.  When you publish:  Customize the "Quality" options in the "Properties" section of the publish menu to the highest quality levels for video and image qualities.  

Note that the clarity of the video (in my experience) is higher in published mode than in preview mode using this method.  Publish your slide/scene/project to assess the results.

Hope this helps.