The resistance in series with the cap makes a first order filter. The cap blocks the lowest frequencies but the frequency still "appears" across the cap. The larger the value the lower the frequency the cap passes.

The formula is 1/2*(Pi)*R*C where Pi is the irrational number, R would be the 5 ohms and C being the value in Farads.

Even larger caps like you will use in a crossover get broken in just like they would in the crossover. But if you build the crossover and put the 10 ohm resistors in place of the drivers you will do the same thing with all the caps at the same time. You don't have to listen to them either.

Crap! I hadn't thought of that. That is even faster for your crossover.