vhs-bordercontrol, telecide() and (ml)degrain in vapoursynth

[i4004]

here's the good illustration of the new issue, when i try to load audio via .vpy script:
     

vdub2 loads and plays both audio and video without issue (so i think script is valid), while hybrid says it didn't find length ( same as here https://forum.selur.net/thread-14.html ). it then disables video processing tract.

vpy:

# Imports
import vapoursynth as vs
# getting Vapoursynth core
import ctypes
import sys
import os
core = vs.core
# Import scripts folder
scriptPath = 'C:/Program Files/Hybrid/64bit/vsscripts'
sys.path.insert(0, os.path.abspath(scriptPath))
# Loading Support Files
Dllref = ctypes.windll.LoadLibrary("C:/Program Files/Hybrid/64bit/vsfilters/Support/libfftw3f-3.dll")
# Loading Plugins
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/DenoiseFilter/CTMF/CTMF.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/GrainFilter/RemoveGrain/RemoveGrainVS.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/DenoiseFilter/HQDN3D/libhqdn3d.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/DenoiseFilter/NEO_FFT3DFilter/neo-fft3d.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/Support/libmvtools.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/DeinterlaceFilter/TIVTC/libtivtc.dll")
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/SourceFilter/LSmashSource/vslsmashsource.dll")
# Import scripts
import rescued
# source: 'C:\Video\netwr0k video cache\vhs_tdk_240_mamets theater_12sec killing telecide with laced subs.avi'
# current color space: YUV422P8, bit depth: 8, resolution: 480x576, fps: 25, color matrix: 470bg, yuv luminance scale: full, scanorder: top field first
# Loading C:\Video\netwr0k video cache\vhs_tdk_240_mamets theater_12sec killing telecide with laced subs.avi using LWLibavSource
clip = core.lsmas.LWLibavSource(source="C:/Video/netwr0k video cache/vhs_tdk_240_mamets theater_12sec killing telecide with laced subs.avi", format="YUV422P8", stream_index=0, cache=0, prefer_hw=0)

audio = core.bs.AudioSource(source=r"C:/Video/netwr0k video cache/vhs_tdk_240_mamets theater_12sec killing telecide with laced subs.avi")

# Setting detected color matrix (470bg).
clip = core.std.SetFrameProps(clip, _Matrix=5)
# Setting color transfer info (470bg)
clip = core.std.SetFrameProps(clip, _Transfer=5)
# Setting color primaries info (5)
clip = core.std.SetFrameProps(clip, _Primaries=5)
# Setting color range to PC (full) range.
clip = core.std.SetFrameProp(clip=clip, prop="_ColorRange", intval=0)
# making sure frame rate is set to 25
clip = core.std.AssumeFPS(clip=clip, fpsnum=25, fpsden=1)
clip = core.std.SetFrameProp(clip=clip, prop="_FieldBased", intval=2) # tff
# Deinterlacing using TIVTC
clip = core.tivtc.TFM(clip=clip)
# Making sure content is preceived as frame based
clip = core.std.SetFrameProp(clip=clip, prop="_FieldBased", intval=0) # progressive
# Making sure content is preceived as frame based
clip = core.std.SetFrameProp(clip=clip, prop="_FieldBased", intval=0) # progressive
# removing grain using TemporalDegrain
clip = rescued.TemporalDegrain(inpClip=clip)
# adjusting output color from: YUV422P8 to YUV420P8 for x264Model
clip=core.std.Crop(clip=clip, left=0, right=0,top=0, bottom=12)
clip = core.std.AddBorders(clip=clip, left=0,right=0,top=0,bottom=12, color = [0, 128, 128])
# Output
clip.set_output(index=0)
audio.set_output(index=1)

interesting question is how can it figure out length when same script is used, but without loading the audio in the script....ie script with video only