This special is 7 two minute episodes with each episode containing three 30 second short skits. The other 30 seconds are the introduction and voice actor credits.
These are Chibi animations about the third season, in a similar style to the earlier Attack on Titan picture drama. This time however the skits are less repetitive and with slightly better humor. The voice acting and sound are good, the animation is alright as far as Chibi animations go.
Overall I don't feel like this is worth watching, it doesn't add anything to the main series and the humor is pretty hit or miss. Unless you like chibi animations or find the suggestion that a titan can slip on a banana peel to be enjoyable humor, this probably isn't worth watching.