StarCraft is partially a game of processing information. Multitasking is one of the main skills you improve while playing.
First, you need to use hotkeys. Use them to quickly get information on production status and jump to different groups.
With SC2, hotkeys can bind to multiple buildings or groups and you can use the Tab key to tab between them. Personally, for Terran, 1 is for command centers, 2 is used for my initial initial scouting SCV and then for general unit usage, 3 is always barracks, 4 is always starports and factories. 5 through 8 become groups of units in the mid- and late-game.
The above scheme lets you tap 3 and 4 to see production status of the army. Do this and, if you don't see white dots underneath the green building icon in the bottom console, start building something. (What to build is another discussion.) Cycle between your hotkeys to move units and check on production status.
Don't forget that double-tapping hotkeys takes you to the group, Ctrl and a number assigns the group, and Shift and a number adds units or buildings to the group.
Next, you really, really need to pay attention to audio cues in the game. Make sure to turn the music off so you can hear them more clearly.
Finally, note that Space takes you to where the action is. Did you year "Our units are under attack?" Hit space, and you'll be taken to the action. Or maybe you'll remember which hotkey you assigned that group and you can double-tap it.
Hope that helps :)
Actually, I'd say it's the shoutcasters turning off the health bars. You never see replays of the gamer himself because that could cost him performance. Those games are either frapsed live through spectators or they just comment on the replay. So you never actually see the player's settings in a game.
Any pro-gamer worth his salt will tell you that you should have the health bars on at all times.
It makes it much easier to focus targets that are already low and makes it much easier for you to see what unit needs to be pulled back.
And even in macro game the health bars still stick perfectly to the units, so you can still see very well (I'd argue that it's easier with bars on than without) what's going on on the battle field.
Best Answer
Probably not exactly what you want, but you can also hold down the hotkey, and it will rapidly queue up build orders. It can be pretty handy for things like morphing a lot of banelings.