video:change_rate(2.0)
This will make it play at twice its usual speed. Your rate should not be
-negative nor exactly zero. Be aware that once you've set a rate, the player
-will wait for the next frame before considering any other commands,
-so if you set your rate to e.g. 0.001 to nearly stop it, you will indeed
-need to wait 16.67 seconds (assuming 60 fps video) before you can speed it
-up again. This restriction may be lifted in the future.
+negative nor exactly zero. You can set a rate to e.g. 1e-6 if you want to
+in practice stop the video; once you change it back to normal speed,
+the next frame will resume playing.
Integration with CasparCG