[udaaff]

button_btn.onPress = function() { 
	slideShow = setInterval(loadMCclip, 2000);
}

stop_btn.onPress = function() {
	clearInterval(slideShow);
};

Сообщение от Ostgur

function slideShow(stopper){
if(stopper == 0){
var slideS = setInterval(loadMCclip, 2000); // без var
} else if(stopper == 1){
clearInterval(slideS);
}
}

.....