@chisezo:
Hello!
Don't worry! The files of UDL Helper are regularly checked by antivirus programs. You can verify the safety by checking it on VirusTotal. If your antivirus had a false positive, you can add UDL Helper to the exceptions. After that, you'll be able to enjoy easy downloading of videos and music to your computer.
Best regards, YouTube Downloader (UDL Helper) team!