Hey another person with wind tunnel exp... I've never used the term before, but I've used the principle behind the orifice plate before for velocity measurements. There's no need for a pitot probe. I believe that the total pressure is constant in this regime (isentropic) so you can use continuity (vdot == vdot) and bernoulli to get velocity by varying area and taking multiple static measurements.bit expensive but very reliable and easy to use,
also the construction of your fan test chamber is very much like an orrifice plate http://en.wikipedia.org/wiki/Orifice_plate
so you could probably get away without using the pitot probe
To answer your question about the hot film response... my experience matches SuperSilents. The response is excellent, but I do not remember ever using it for free stream velocity measurements. We backed that out using tunnel pressure taps - using the method referred to above.
EDIT: you need a good atmospheric pressure measurement too
EDIT: I just watched the videos... awesome setup - but now you have to watch the vids for the review. seems it'd be nice to use the serial bus for the anemometer and an a/d card for the rest, throw together a quick data acquisition program in labview and instant results - I miss my lab