Henneko BBS consists of 13 short clips each around 40 seconds and focus on Tsukiko eating and Yokodera being a pervert. Even though they were initially used as advertisements they aren't very representative of the anime and should not be used to decide whether or not to watch the anime itself. Considering it takes less time to watch all 13 episodes than a single episode of a normal anime it's not a big commitment and can be fun to watch if you liked the anime and want to see a bit more of the characters. However don't expect too much because of the very limitedlength of these clips.