How to use APC for Media Mail
1. At home (or, optionally, at USPS if you're lonely): weigh packages, mark poundage upper left corner (where the stamp will cover it) (Anything under 13 oz send 1st Class Mail). Stamp "Media Mail"
Count how many of each weight.
2. At APC:
2.1 Pick "buy stamps"
2.2 Pick "other postage amount"
2.3 Punch in amount for one poundage category, e.g. $2.13 for 1 lb media mail
2.4 Tell APC how many you want. This may take several passes, if the APC is limited to printing 5 stamps at a time.
2.5 Repeat 2.3 - 2.4 for each poundage category
2.6 Apply stamps, put in tubs, and politely leave on counter.
3. It is considered poor form to taunt the people waiting in line, but you can feel silently smug.