MediaPi, that file is not SD, it's HD (720p 4:3). There's no higher resolution for that series...
Do you think size is low? It's a 750MB file for a 25 minute episode...
Remembers that it's not a movie, it's just an episode from an old anime series (1988) that has been edited in Bluray recently, in a 960x720 resolution, mantaining it's 4:3 original form factor.
Also, the first video, that one you commented in youtube, is in FullHD 1920x1080, a near 7GB file (remember that anime always take less space after encoding, a lot less colour information to code compared to real-life image).
Being an "easy challenge"... well, Hi10p isn't a easy challenge for any media player. Altought in a lower resolution than 1920x1080, Hi10p decoding requires a lot of CPU power, and the fact is that until a bunch of days ago, we all where thinking that the 847 NUC couldn't do Hi10p decoding... but we were all wrong