In addition to those things I pointed out about Warner Bros.'s Sesame Street releases (and what dr.tooth said about them all being Elmo videos), I've noticed that all but the Elmo's World and upcoming bugs video contain things that were on the recent 40th anniversary DVD. Part of me wants to think of this as a coincidence, and part of me wants to think this was done on purpose.
The springtime release had Guess the Seasons Song. I guess that was to be expected, as there aren't many segments that are just about spring (it's a shame that Spring is Here wasn't included in addition to The Cookie Bunny). The Bert and Ernie's Great Adventures DVD has the segment that was on the 40th anniversary DVD, but I can forgive that if they plan to make a second volume and get every B&EGA segment on DVD (because to have every episode on "complete" DVDs, they'd have to double-dip). The Best of Elmo 2 has four segments from that set, and I feel that is overkill. And of course it's been announced that African Alphabet will be a bonus feature on the upcoming alphabet release.
As I said, that one should have included ABCs of the Swamp instead. The only video release of that is the long out-of-print The Alphabet Game. Or it could have included Kermit and Joey singing the alphabet, though that has been released a few years ago (just not on the anniversary set). Or they could have chosen Don Music's version of the alphabet song, or the rare skit where Kermit tells Bob that the alphabet is the secret of life, or one of the other segments (besides the Joey one) where Kermit and a kid or kids recite the alphabet. Or even if not a Kermit alphabet segment, they could have chosen Rappin' Alphabet or Ernie writing an alphabet story or Biff trying to get Sully to say the alphabet.