how to use denoise script from site

[horrormaster34]

How would I use this denoise script that appears on the Avisynth website (http://avisynth.org/mediawiki/Denoisers):

source = last
pred = source # to get stronger denoising, put denoisers here, they will change how motion vectors are predicted

backward_vec2 = pred.MVAnalyse(isb = true, delta = 2, pel = 2, overlap=4, sharp=2, idx = 1, truemotion=true)
backward_vec1 = pred.MVAnalyse(isb = true, delta = 1, pel = 2, overlap=4, sharp=2, idx = 1, truemotion=true)
forward_vec1 = pred.MVAnalyse(isb = false, delta = 1, pel = 2, overlap=4, sharp=2, idx = 1, truemotion=true)
forward_vec2 = pred.MVAnalyse(isb = false, delta = 2, pel = 2, overlap=4, sharp=2, idx = 1, truemotion=true)

maskp1 = mvmask(kind=1, vectors=forward_vec1, ysc=255).UtoY()
maskp2 = mvmask(kind=1, vectors=forward_vec2).UtoY()
maskp3 = mvmask(kind=1, vectors=backward_vec1, ysc=255).UtoY()
maskp4 = mvmask(kind=1, vectors=backward_vec2).UtoY()
maskf = average(maskp1, 0.25, maskp2, 0.25, maskp3, 0.25, maskp4, 0.25).spline36resize(source.width, source.height)

smooth = pred.fft3dfilter(bw=16, bh=16, ow=8, oh=8, bt=1, sigma=4, plane=0)
source2 = maskedmerge(source, smooth, maskf)

source3 = source2.MVDegrain2(backward_vec1,forward_vec1,backward_vec2,forward_vec2,thSAD=400,idx=2)
source3
ttempsmooth(maxr=7)
gradfun2db(1.51)