Instead of picking apart my examples, please try to understand the idea I'm trying to get across, which is how the different shapes of different pieces affect forward movement. Like XaeL mentioned, I have a hard time coming up with legitimate "bad" examples, these should be taken more as an illustration of how the pieces affect the field shape than specifically how to stack in a given situation. I'd have to play and record some games, and who knows how often I'll have a good example, to get proper examples.
The main point is that XaeL is making decisions he doesn't discuss in his videos; the things he does discuss are important and useful, but somebody trying to follow just the words without those behind the scenes decisions won't get the full value out of it.
I'm sorry that my examples were pretty much terrible

Note: this is relatively minor and not a criticism, just a suggestion for making the whole thing more complete. Keep up the good work!
A couple specific responses:
Of course you want to avoid crenellations, but the point of that diagram is to illustrate how when you have to make holes you can make progress while making those holes if you use your "extra" minos well.
T vs S: yes, a J or I makes a better downstack in that specific situation, but the point is to illustrate how the S perpetuates the shape on the right and the T alters it. Also if there were garbage holes under the right side, the I or J would be worse solutions for sure since the J will add at least one more line to clear before you reach the hole and the I could potentially add two.
There are many cases like this, but I don't know how to go about compiling a complete list of "good placements." The point is rather to be aware that this concept exists, and watch for it in your play. When something gets messy, look at how the previous pieces affected why you couldn't straighten it out easily. Pay attention to unintuitive leaves and things like that. This is good for general stacking in all cases.