Duct Tape was never designed for ductwork. The big question: why is it still being used? Getting a proper duct sealing will help keep your home cooler in the summer and warmer in the winter. Duct Sealing should be completed only by a Certified BPI Professional.
According to the Department of Energy more than 30% of the Air that goes through the duct is lost before it makes it to the final destination making rooms uncomfortable and keeping your system running longer than needed. Don't just hire the typical HVAC company that does the work only 70% right. Hire the professionals. Ask for your duct work to be tested by a BPI Professional using a Retrotec Duct Tester to verify the results.