I'm an absolute idiot, chessexplained is simply looking at the computer analyze move by move. I assumed he was having it annotate as he played because he was able to relay the computer's lines so quickly. Presumably he's using something a little stronger than my 2010 Macbook Air :). Thanks for the help, anyways.
I no longer need to know about the removal of the D for diagram and such since I'm now just writing out the annotations myself as I look at the generated eval. Perhaps someone would like to answer this question for progeny's sake, though?
Lately I've been watching the chessexplained youtube channel:
https://www.youtube.com/watch?v=qEy99vNm_as
In his videos his program (Fritz?) is annotating the game as he plays it, allowing him to immediately review the game after he finishes. It seems like an extremely useful feature, as long as you weren't able to see the computer's analysis as you played.
Is there any way to do this with SCID? I'm using SCID vs Mac 4.12.
Edit: on a related note, could anyone tell me how to remove the engine generated balance evals without removing the comment-based number evals? Chess.com's chess interface does not accept +, -, nor the D that is put at the end of some lines.