To be honest, I had exactly the same troop selection problem mentioned in the video, until I found out that tapping the right trigger will allow you to scroll through all the different types of units you've currently selected. Why they never mention this anywhere in the game is an annoying mystery, since once you learn about this it cuts down the tedium of splitting your main force up to attack from multiple fronts considerably (my favorite use is to have all my aircraft fly straight to the enemy base and shell the shit out of it while my vehicles split up and shell the shit out of the same base from two or more different directions while the enemy forces are distracted by my aircraft shelling the shit out of them. And then I call in MAC blasts and air strikes. you can guess the rest).
I also would like to mention the annoying fact that there's no proper way to lower your troop count. If for instance I'm trying to build extra tanks or aircraft and I realize that I've hit the fairly arbitrary population cap, the only method I've been able to come up with to lower it is to select small groups of marines and send them in one at a time to die. This does have it's advantages, since it lets me force my soldiers as close to committing hara-kiri as the game allows, and gives my enemy high morale at the weakness of my army only for that hope to be absolutely crushed once an entire regiment of tanks drives right up their ass. But I still would rather have an easier and less time consuming method of recalling troops (and I could still do the hara-kiri tactic anyway if I wanted to).
Anyways, really enjoyed the video, hoping you'll review Mad World at some point.