All these calls you have to CF.widget I would replace with GUI.widget.

CF.widget("FF_Speed").label=speed+"x";

GUI.widget("FF_Speed").label=speed+"x";

If it so turns out that the widget tag you declare is not available on the current page, your code will throw an error.

I'd create a function to handle this and fail silently.

function updateGUIWidgetLabel(tag,value) {
var w;
if (w=GUI.widget(tag)) {
w.label = ''+value;
}
}

then, this line
GUI.widget("FF_Speed").label=speed+"x";

becomes a bit more readable.

updateGUIWidgetLabel("FF_Speed", speed+ "x");


same thing applies for visible property.

CF.widget("Pause").visible = false

function showHideGUIWidget(tag,visible) {
var w;
if (w=GUI.widget(tag)) {
// (true && visible) will do type coercion to boolean type.
w.visible = (true && visible);
}
}

This
CF.widget("Pause").visible = false

becomes...

showHideGUIWidget("Pause",false);