Coach Justin Burke is the Co-Offensive Coordinator and Tight Ends Coach at the University of Texas at San Antonio.
The entire video of drills he uses for tight ends in their passing game is available on Glazier Drive.
Coach Burke's philosophy is that you need to break down and drill every aspect of tight end play in the passing game, including:
Stance/start, 1st level release, 2nd level release, speed, stem, breaking point, separation, catch, and YAC
The video below focuses on release drills.
Here are some other takeaways for the foundations for tight end play.