You are trying to fix a non-existing problem here. We have been using ffmpeg this way for years without any problems. Moreover, the computers on which we want FFMPEG to be super fast (because the computer is slow) are precisely the ones which don't support SSE2. Morever, that codepath is also used on many non-x86 archs so it's actually quite well tested on FFMPEG side, so there isn't much to worry about there.
If you can find files that are actually problematic to replay in MediaPlayer, we can reconsider this.
