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Do I need both the softwares or either one is good. Converting it to mp4 is not a concern.

You need both. SaveHollywood is a screensaver and Wallsaver is an app that allows you to set screensavers as your desktop pic. Just configure SaveHollywood in System Preferences and then select it in Wallsaver.
 
Save hollywood is showing an error message, "You cannot use save hollywood screensaver on this computer, contact developer."
 
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