Using the H.265 (HEVC) codec can make a file 30-50% smaller than the older H.264 standard without losing quality.
The length of a 14.65 MB file depends on the (the amount of data processed per second). 720p mp4(14.65 MB)
Are you looking to a specific video to this size, or are you trying to identify a particular file you've encountered? Video File Size Calculator (by format) Using the H