Photos are what families print, frame and post. They're also what studios use most on websites, flyers and enrolment pages.
Video: for energy and enrolments
A short highlight reel shows music, movement and atmosphere. It's often the most effective thing to post when enrolments open.
Both, if you can
If budget allows, combine full photo coverage with a short highlight reel. If you have to choose one, choose based on how you'll actually use it over the next year.