I was watching the GSL recently and it turns out there's a pretty serious bug/glitch the terrans can use.
 
Basically, if you have a damaged mechanical unit in your medivac along with a number of SCVs which are set to auto-repair, the SCVs will start repairing the damaged mechanical unit.
 
So you can drop 3 hellions into an enemy's base, pick them up, and repair them as you manouver around. You can also repair tanks this way (you can't do that with thors since a medivac with a thor is unable to carry any additional units).
 
I seriously doubt Blizzard intended to enable repairing damaged units while they are in a dropship.
     

Just made another topic with this.  Don't think it's a bug, just a little trick.  Not a huge deal, just keeps you from having to stop somewhere to repair.

On another note, I don't watch Husky and that video definitely convinced me not to.  Nearly 3 minutes to describe something this straightforward?   He just talks too damn much.

I don't know if you can consider it a bug. It makes sense. The SCVs repairing a unit in a ship. Nothing weird about that.

Only Zerg has bugs.

" Only Zerg has bugs. "

Well it isn't mentioned in the next patch notes.   Maybe they'll address it soon.
 
 http://us.battle.net/sc2/en/forum/topic/1213111662