Some movies, like the one on the left, play automatically. Press the space bar to stop and start these movies, or use the control bar below the movie.

Virtual reality (VR) movies, like the one on the right, do not have a control bar -- instead you rotate or otherwise change a block by clicking and dragging the cursor (left and right, or up and down) inside the movie.  Small, labeled arrows above each movie indicate how you can change the block.  

Play movie

Rotate block