I was saying I'm more familiar with Warcraft 3 units and don't know what a lot of a little is in Startcraft 2 units. And I'm glad that gave you an idea.
Instead of moving the camera to the unit, I moved the camera to where the unit was going. This removed the camera falling behind for me, but I don't know it will fare with a speed of 15 (not sure how fast that is in Warcraft 3 units).
I think either thehive or wc3c has a system when you can draw shapes and check if a unit is in them. I'm at school right now and both of those sites are blocked so I can't view them to check for you.
Wait, I just read what I said and realized that you could have interpreted it two ways. The way I meant was kicking a bomb, like you pick up the powerup for kicking and when you run over a bomb it moves forward as far as it can.