Hello, and welcome to digitalfaq.
Some problems here.....
Thanks for the sample link. Many readers won't venture to download from outside sites, especially those that display mandatory cookie permission dialogs, logins, ads, etc. You should post samples directly to this forum. Read here for posting images, videos, and other attachments:
http://www.digitalfaq.com/forum/news...ly-upload.html.
The sample is very poor quality, but you already know that. It's also damaged through lossy encoding and several processing errors. The video is lossy encoded at least twice, resulting in more quality loss. It was encoded with the incorrect field order, then resized while still telecined, so the original telecined (interlaced) fields are permanently blended. The incorrect field order displays stutter, double images, and field combing on motion. Sorry to say, this damage can't be repaired in Avisynth or anything else.
You can't expect good quality from Boilsoft or lossy MJPEG encoding, neither of which were designed for edits or cleanup without further loss.
You didn't tell us how you captured the VHS. Why is the frame size 720x540 ? Many Avisynth filters require mod-8 frame dimensions. The height of 540 is not mod-8 (mod-8 = a number that can be evenly divided by 8 with no remainder). What do you want for your final product? 720x540 is not valid for DVD, BluRay or AVCHD. Audio in mp3 format sampled at 44.1Khz wouldn't be valid, either. I'm guessing that you want playback via PC or external media server only.
Sometimes incorrect processing can be fixed up (somewhat), but in this case many elements can't be fixed. Do you have your original capture?
Let us know how you captured, and try posting directly in this forum if you want further comments from other readers. With more information about your processing, you can get more help.