If you check in at the counter, the agent will get a popup screen with the re-routing alternatives offered and the compensation. Normally they offer reroutings using a LH/UA flight combo. Perhaps even US, but definitely no AA unless there is no other connection that day.

If you already have the nice 744 seat 5D reserved, just checkin at one of the counters in FRA and innocently ask if the flight is overbooked. If the agent is in a good mood and no one is queing behind you, he/she will even look up the overbooking situation for your flight in each class and in total. Try not to check any luggage or if you must, get it tagged with the blue volonteer tag.