From experience i can tell that a good tutorial consist of a lot of little things done right, and i'm full of admiration because "Sentdex" avoid many popular mistakes
Many video tutorials offer a blank screen (or the programming IDE) while the narrator tells something. Sentdex took the effort of cutting and editing the video, doing close-up's of himself as for the introduction and later making the code the main actor while putting himself in a "picture in picture" box. This sound not hard but is actually a lot of (unpaid for) work.
While online video tutorials have their usefullness (things like showing how to navigate a complex user interface), for information alone, specially about coding, text is usally better suited. It is far more simple to read text (and source code) than watching, (and re-winding) a video. Thankfully, the Python3 pygame tutorial series works as well without the videos, because all the necessary source code examples are visible in the blog. I wish more youtubers would take this effort.
Screen size: Simply screencasting while you code and explain result in a near-not-readable font in most cases. While it sound trivial to "just increase the font size" it is not done in countless video tutorials. Here the fonsize makes sense.
Focus and lenght: Trying to explain too many details is as irritating for the learner as is letting out too much "obvious" facts. I think the Sentdex did it right with this series, eight easy to digest parts mostly improving one and the same example.
Critique: The only think i miss is a link explaining the license of code and tutorial and a link to the whole code examples on githup or another repository. Very cool: On the youtube video description is a Bitcoin-address for donations.