Shoot those large balls first, they should be staying at the top for a while. Then take out the ones that made it down first and continue doing so.
Run right straight away, the left ball will bounce back up so don't worry, but the right one will get out if you don't take care of it. Shoot it and slowly edge left while you take out anything that comes close. Shoot open the three containers at the top if you haven't already to get the rest of the level.
Don't shoot those glass panels on each side, instead shoot through the small gaps until they are all gone. Some small balls will most likely drop through once in while. They will also most likely drop all the way to the bottom straight away. A small trick is, instead of taking the ladder down, stand on one of the openings and shoot the rope up. This way you will hit the ball underneath you if it happens to be nearby.
These two ball are actually quite slow, the only tough thing is that they do not bounce evenly on the steps and you are often very close to them. It's quite easy compared to some other stages from before.