Check that your security software is not blocking the application. You may need to add YTD to your allowed programs list or temporarily disable the firewall to test the connection. Software Updates:
This is the most common solution for the error. Older versions of YTD used an offline license key. v7.3.0.1 forces online validation. To "fix" this, you must block the validation servers. YTD Video Downloader Pro v7.3.0.1 Fix
Open the file named hosts (no extension). Check that your security software is not blocking