NEON doesn't provide IEEE-compliant FP, only single precision FP ops are available (and don't support all rounding modes for instance). You'll have to wait for ARMv8 processors to get SP/DP IEEE-compliant FP.
You can compare SSE vs NEON with FFmpeg by choosing a format that has been optimised for both ISA.
It should also be noted that I know someone working in a company doing post-production who told me they are using some nVidia farm that is based on ARM CPUs, they are probably using this:
http://blogs.nvidia.com/2011/12/meet...velopment-kit/