This really has no real meaning to the actual series or is any step closer to their goal.
It's much like a Lucky Star moment that's just for fun.
This is just brief as it is one episode.
The music is still the same as it was before, except the ending was played... backwards (just the video was)
I personally enjoyed it because it really made me laugh and it was something different from the original series, as I also love the character design from Angel Beats!.
I didn't like some parts because much of it was pointless, and it seems as if it's to keep Angel Beats! alive just a little longer than it normally would have.
It's also interesting how the characters act in this (keep an eye out for it... if you don't notice it... you must be dense..) because it's much more different from the series.
Overall, It is just a filler or alteration to an episode of the original series. Nothing too interesting happens. I'd suggest that only the hardcore Angel Beats! fans watch this. (I'm just trying to leave out as much spoilers as possible)
BY THE WAY.... MyAnimeList, you should keep the listings of anime updated better. I've already watched this a couple hours ago fully subtitles yet the Add Anime to List will not let me say I've watched this.
