JES deinterlacer is old and not very efficient/has a bad quality deinterlacer.
Two of the very best options you can get for free on osx are from Handbrake and avidemux:
Handbrake uses yadif-- a decently high quality motion estimated deinterlacer on frames with lots of combing, and a low-pass 5 filter on frames with not much combing. Low-pass 5 is just a blur filter, and it will result in more detail.
Avidemux gives considerably more options and all the same high quality x264 codecs as handbrake, but also other options for deinterlacing. It gives access to yadif, low pass 5 and tdient among others.
The absolute best deinterlacer you can get for free (also takes a while to finish) is tempgaussmc, but the easiest way to access that is through aviproxy on windows, and not osx. It's an avisynth filter, and via the proxy it can be used with avidemux. It's a motion compensated deinterlacer that uses the edi interpolator and temporal gaussian blurring to refine edges to reduce edgy lines that yadif, low pass 5 and especially tdient can leave. It also doubles as a bobber, meaning that it will take each interlaced field in the vid and make it into its own frame, so makes the vid 60p.