Even using standard encoders, the H264 got a lot of compression parameters, I mean dozens of them you can edit into thousands of combinations so to have file very small with still decent quality - tuning H264 compression (with existing standard encoders) being a job on its own, humans can do it best because evaluating results with eyes.
There is H265 which will be supported by chipsets in a future, so H264 will be outdated in a few years, but software-only H265 implementation run too slow to be usable by conumer today for ex. in phoens, tables, old pc's.
Let your friend having made something compatible with current H264 decoding soft/hardware (so immediately playable in flash etc.), that would be a special encoder which is different from current encoders (better result with same parameters) but providing an H264 compatible output.
Note that H264 is very complicated, the C++ source code of an encoder here:
https://github.com/cisco/openh264/tr...coder/core/src
Doing better than this, still playable by H264 hardware, it is not easy task really, so you may expect people to be skeptical or at least need more info.