Part of the lack of responsiveness you got is that your initial post of watching VHS on PC wouldn't involve OBS (other than possibly as a recorder, but there are far simpler ways/tools for recording a video input stream than OBS
Typical old school VCR used RCA cables, 2 for video (red and white) and one for audio (yellow)... typically... from memory. Some more advanced (old) models had S-Video outputs. So, first thing to determine is what is the output options on your VHS player. Ideally you'd have a newer VHS player that has HMDI output (which includes audio) and a HDMI capture card (USB 3.0). But, your mileage will vary.
Once you determine video output source, then you need an adapter to getting into PC.
In this forum, search and see article on USB Hub Controller contention - something to be aware of and not trip yourself upon
As for sound - are you outputting/capturing sound, or just the video? if just using 2 RCA cables, then you are probably only capturing video.
Again, all of this has nothing to do with OBS
Where OBS could come into play, is if you wanted to add overlays (Titles, etc) to the videos, or add picture, etc. If you are doing a simple video capture, I'd think OBS is the wrong tool (overly complex for what you are trying to accomplish based on what you described and better alternative available as you've found)
