YouTube constantly changes it's algorithm. This can cause the 'Signature problem (4003)' error.
We did our best and have solved the problem immediately. Please re-install the program and enter the YouTube link again. Follow the steps bellow:
- First, uninstall the DVDVideoSoft app: Click Start → All Programs → DVDVideoSoft → Uninstall (check the box 'Select all')
- Download and install the last available version on the website
Thank you for your understanding and support!