Scanlines on interlaced source

[Dogway]

Hello, I ripped a DVD guide of a game, it is interlaced so I thought on using QTGMC, but it was slow and results were far from desired. Then I thought about adding scanlines, and I think I'm almost there (I'm still open to suggestions), but the main concern is about the bob-flicker and certain "jumps" every few seconds, is this supposed to be correct?

Now after testing a bit it seems these "jumps" are something related to mpc-hc. I used a simple bob() and in avspmod there's flicker, then I preview the script in mpc-hc and even by frameskipping there's no flicker...

source 9Mb:
http://www.mediafire.com/?mfci31cc4uwzenj

separatefields
Deblock_QED(quant1=30, quant2=40)
LSFmod(defaults="slow",strength=50,edgemode=0,soothe=true,ss_x=1.0,ss_y=1.0)
raw=last
weave(interleave(last,mt_lut("26",u=2,v=2)))
SmoothContrast(0.2,sat=0,limit=true)
LumaMask(SmoothLevels(16,1.2,235,16,235,smooth=10,show=false,dither=100,limiter=0),raw.bob,black=64, white=255, brightfilt=false,show=false)