Video-laryngoscopy often provides better laryngeal exposure by navigating the curve around the tongue. However, tube delivery tends to be more complicated than with DL because flatenning of the primary (oropharyngeal) and secondary (pharyngo-glotto-trachea) curves is not usually needed. In addition the operator has to deal with the lost of depth perception that occurs when looking at a 2D screen.
Here is how to troubleshoot the common scenario of visualizing the cords, but being unable to intubate the trachea. Take a deep breath and apply these steps: