Just thought I'd chip in, there's a good chance that this is related to the dimensions that you set your video at.
For example: if you set your video to be 640 X 480 pixels (which is commonly the default) and then exported your video at 1280 X 720, then your maximum resolution will be the default 640 X 480 pixels.
To fix this: In your video editor (which I assume you are using) add the video file, and set its dimensions to 1280 X 720. When you are finished editing, export it at 1280 X 720 as well.
NOTE: this will only work if you have your video recorder set to record at high resolutions (720p, to 1080p) otherwise, it will just keep the default 480p resolution. Hope this helps a bit.