Great job, Jim! If you create these videos in a classroom, is there a whiteboard or a chalkboard? That would allow you to leave the Chinese characters or Pinyin on screen while you're talking, which would make it easier for students to follow you. We can look at the Pinyin of ǔ while you're pronouncing it; we no longer have to remember which vowel and which tone you are now saying.
Thanks for the video. (I clicked on the "like" button.)