I love using a flipped learning approach in piano lessons.
During piano lab, having students watch quick video clips about musical concepts is a great way to introduce or review concepts.
Having students preview concepts in advance allows for more repertoire focus during private lessons and accelerates learning with repetition.
Below are some great intermediate level piano video resources.
Lengthy explanations can quickly bore students and adults! I find the most effective videos are multi-sensory, brief, and use simple language. Here are several I have hand-picked after browsing hundreds of tutorials on YouTube.
Intermediate Music Theory Terms and Signs Videos
CK Tempo - brief definitions of rit. ritard. rallentando, repeat, staccato and slur