Skills and drills are added at each level as the player and team mature, but once introduced are to be used practiced for the rest of a players career. For example, catcher drills and skill are not appropriate at the TBall or Rookie level since runners can't advance on a pitch. We don't teach these skills because we need to spend our time developing the precursor skills of catching and throwing. As the players move to minors, catchers need to learn the basics of catching and continue to hone those skills for the rest of their catching career. As catchers advance their mastery of earlier skills need to be maintained while adding new skills. E.g. as the advance through the older divisions the new skills needed added to prevent runners from advancing.
Most highlight videos put an emphasis on hits. This makes sense since a typical baseball games has 51-54 out, but only 7-9 hits. Since most of those out are "routine", they don't get much attention, only the exceptionally hard out make the highlights. Youth baseball players, really need to focus on how baseball outs are made, since that's how we end an inning and keep the number if hits (and runs) down. Please focus on routine plays when watching games with your children. If you look at the highlights below, try searching for "defensive play" to show your children.