The legend probably doesn't have enough cpu grunt to play HD material. RockPlayer does a very good job, I've tried some 1080p samples and even Killa just for fun, it tries to play them but the cpu can't keep up. Even if HTC release an app that does video playback of all formats it won't upgrade the phone cpu.
RockPlayer works great and its available as a free version.
RockPlayer works great and its available as a free version.