Reading about the concept of chunking in teaching reminds me of many bits of advice I've seen about effective design of PowerPoint presentations.  Chunking is simply organizing bits of information logically so learners can take them in more easily.  Actually, chunking is something all humans do naturally as they automatically recognize patterns and groupings in new information.  My favorite example was in a psych book I was teaching 20 years ago:  world chess experts could recreate a chess board, putting all the pieces in the exact right spots after very short glances at the board.  Chess novices couldn't.  Duh.  But the real interesting part was that the experts were NO BETTER than the novices when the pieces were arranged in random spots unrelated to a real game of chess.  The experts could recreate an actual game layout because they were familiar with all the likely patterns of arrangement that could occur.  So what they took in was really along the lines of, oh, yeah, it's one of those line ups.  Pieces placed randomly on the board were just as hard for them to remember as a couple dozen seashells randomly arranged on the beach.  (That seashell thing I just made up as a comparison--it wasn't in the actual study in the textbook.)
So teachers should try to create recognizable patterns for students instead of confusing, random non-patterns.  This means screens/slides should focus on one main topic, include no extraneous bits, and follow a logical outline.  To me, it doesn't matter whether you're making a PowerPoint to present in person or a higher-tech screen capture to include in a video lecture for an online course.  The organizational guidelines are the same:  KISS!