&preloadbitrateflag can be used to change the pre-load target bitrate for scenes. You can set this higher or lower, or set to 0 to disable pre-loading all together. I'd strongly avoid setting this to 0, as it can cause the video to stall out all together.
&preloadbitrate=500or whatever, where the value is in kbps.
0disables preloading the scene.
-1allows for unlocked bitrates during preloading.