Dont be too slow when speaking. slow doesn't equal to clarity. Watch any englishman's videos. eg: Ramsay gordans videos. speaks fastly but clear and loud.
if you too slow its boring to watch and hear. remember our brain can process easily anything even if you speak fastly. but its should be clear and crispy. hope this helps when you create your next video. I actually thought something wrong with my youtube playback setting. no offense