I noticed there are two types of video clips teaching you how to pronounce a word or say a sentence, one by a native speaker in the real situation, another read in the standardized speed and intonation. I found difficult to catch the shape of their mouths while watching or listening to the audio-visual assistance. I wonder there would be a third type of video clip demonstrating the word or the sentence in much slower speed plus displaying the shape of the mouth whilst its demonstration? I think it would help a lot.