I understand most of the abbreviations exampled here, it's the ones for Buffy and Angel I struggle with.
I was just wondering about this. I always use AtS and BtVS because writing the whole title is just draining (pure laziness). Or when referring to episodes OMWF, IWRY...IOHEFY (lol). Took me ages to finally get what IR,YJ was. On the opposite side, it took me years to understand what Rm w/a Vu meant. I seriously thought they were just jumbled letters for the longest time. I can see how that would get very confusing.