I've recently discovered saved searches and the power that this feature can bring to the entire TD platform. It would be great to see a video about the range of possibilities for advanced searches and how they can fit into a workflow.
It looks like the Toodledo sync is a Pro feature on Task Unifier. You probably need to upgrade first before entering your Toodledo credentials. If you did upgrade and the sync still doesn't work, you should contact Task Unifier's customer support so they can fix the problem.