In this case, it runs using X11 on OSX, which is a terrible way of making software ;)
PyDev seems to heavy to me when you need to write a standalone script and too buggy at evaluating module dependencies resulting in bad tooltips. Ipython notebook doesn't have this problem because you evaluate code as you develop, so tooltips come from object introspection.
It works out of the box and also supports javascript/html/css/... so is ideal for developing webapps with a python backend.
Ninja looks nice, but nothing I saw in the screencast makes me want to make the jump.
There is a big difference with PyDev/Aptana that is not apparent in the screencast: its lightweightness!
* it is a 1.3Mb download (vs 126Mb).
* startup time is ~2s (vs 30+ seconds)
* memory footprint is ~28Mb after startup (vs 400Mb)
Now I'll definitely try it.
Update: the memory quickly jumped to ~120Mb usage, hope it's not a memory leak.