Why is x264 GPL licensed instead of LGPL like FFmpeg? It would make x264 the de facto H.264 encoder.
The GPL is used for historical reasons; relicensing would be hard, obviously, because we have to contact everyone who ever wrote a line of code. Ironically we are doing that right now, but for a dual-license scheme (GPL/Proprietary).
The reason we didn't choose LGPL for the relicense is because one of the main devs (not me) refused; he saw releasing the source as LGPL to be effectively throwing away any chance to ever make any money off of his work, while keeping the code as GPL would at least reserve that option for the future. The dual license is a good compromise IMO; commercial applications can support development through license fees while free software gets to use it for no cost.