The original Q was a good one. The jaggie issue has a *lot* to do with sampling the sensor and NOT THE COMPRESSION DATA RATE.
To summarize : On the two aiptek's I have, the Action HD and the A-hd+, the 720 modes shoot a wider view, for one thing ( also not on the data sheet !!! ) , and the 720 mode does a horrible downsample ( or lack there of ) from the sensor.
Aiptek may even be avoiding a proper demosaic on the 720 modes, and just doing a pixel skip. The sensor is 2500 or so wide, and it seems they just do a divide by 2 ( skip by 2's ) to get the 1280 across for 720p.
The 1080 mode, which is actually 1440 pixels across, seems to use the middle 1440 pixels, and hence the narrower field of view. The 1080 mode looks better, maybe because the camera has time to process more due to the lower frame rate. Just a guess, only aiptek knows the answer to that.
Anyhow, the cams look good for the money. I hope I helped explain this in a not to technical way.