Well, the whole thing is great, even with a limited cast and no inserts from the show.
The video includes parodies of Super Mario Bros., Angry Birds, Dance Dance Revolution, Rock Band, Pac-Man, and World of Warcraft. It also includes a racing game sequence, which I'm not sure if it's based on any speciffic go-kart games (I want to say it's based on the Mario Kart games, and yet I'm not entirely sure).
I wish it could have referenced a few more classic games, or even had some gaming sequence in the classic 8-bit (or lower) style. The Super Mario Bros. parody sequence resembles The New Super Mario Bros. Wii, and to me the Pac-Man parody kinda looks more like the recent Pac-Man Championship Edition than the original or Mrs. Pac-Man, at least by the structure of the maze (actually, now that I think about it, I think the Atari 2600 release of the game had the maze look like that, though it's definatley not an Atari style). Sure, New Super Mario Bros. Wii and Pac-Man Championship Edition are among the best games in their respective franchises, and certainly the best of the more recent games in those franchises. It's a shame they didn't work in parodies of Sonic the Hedgehog or Pokemon.
The new character ABC-more is a funny character, though he is a bit awkward. He keeps saying that he's the "greatest alphabet expert in the world", but keeps getting things wrong. In fact I'd say he gives Grover (and even Mr. Noodle) a run for his money when it comes to getting things wrong. There are times when he gets items that don't start with their respective letters, as if he's desperately trying to get everything so he'll surely win... But then he also keeps stubbornly avoiding words that DO begin with those, sometimes getting the items mixed up with other words (like thinking a muffin is a cupcake), and sometimes thinks the other characters are trying to trick him when it comes to certain words (whether the words do or don't begin with the respective letters). He's still a funny character, but for an "alphabet expert", I really can't believe how wrong he is.
Among the bonus features is an "Alphabet Storybook" which lasts 47 minutes (according to the packaging... The packaging actually says how long one of it's bonus features lasts). I've only looked at a little of it, but according to Muppet Wiki it's an animated adaptation of a series of Sesame Street letter books. I wonder if that was previously released on an exclusive DVD at Toys-R-Us, like the other animated storybooks included as bonus features on recent DVDs.