You need 50 points to keep going into level 2, 100 points to get to level 3, then it's a free for all until the time runs out. Use left and right to catch the turds. Plungers give you 5 extra seconds, wrenches give you 10 extra seconds.
Turds are 1 point each, but each one you miss will take 1 point away.
Level 1 is 30 seconds, level 2 is 25 seconds, level 3 is 20 seconds.