You can see some differences in the 360p and the 720p versions in the encoding information.
I have to imagine that the Roku is processing the 720p encoding information properly, as the 720p video is perfectly valid.
Does it have to do with CABAC? (Which the 720p+ versions use)
Format profile : Baseline@L3
Format settings, CABAC : No
Format settings, ReFrames : 1 frame
Format settings, GOP : M=1, N=60
vs. 720p info:
Format profile : Main@L3.1
Format settings, CABAC : Yes
Format settings, ReFrames : 3 frames
The 720p video doesn't define a maximum bit rate either for the video and audio streams.
The 720p video also includes additional 'Title' and 'Encoded date' fields that the 360p version doesn't include.
Could the header differences be parsed improperly within the Roku? Or can their media player not handle the encoding type for the video stream?
I'm guessing their media player code can't handle the encoding. I'm tired of waiting on Roku to fix handling "odd" encoding schemes, and I don't expect this to be fixed in any reasonable amount of time, especially considering they hardly ever respond to questions in the forum.