Avi Steering
From sNr Wiki
Some ponies try and do ponyplay without a mouse, which is really not recommended. For effective training, the pony needs to conduct all training using a mouse, in mouselook. As a special case, ponies taking part in polo competitions can be allowed to use avi steering.
To use avi-steering, grab the back of your avatar with the mouse and drag. If it doesn’t work then go to Preferences | Move & View tab | Movement Single click on land, set it to: "No action".