If I may pop in with an idea, can you try different Codecs in Bandicam? The reason why I am thinking this, is because most codecs are designed to vary the bitrate depending upon the changes it detects in the frames (more changes = allocate more bitrate) [this is in VBR mode, which Bandicam defaults to, I believe].
In the past, some codecs had issues when creating Keyframes (Keyframes, or Information Frames, are created when there is a large change in the data coming in (the changes on the screen)). I have not experienced this with Bandicam personally, but I have experienced this in other recording programs before I found Bandicam. Back then, switching to a different codec usually 'fixed' the issue.
Are you using some sort of pass-thru device (USB adapter, etc) for your VHS feed? Sometimes, these devices will think that STATIC on the screen is 'the end of the tape'. This might be happening as well. There might be settings for your device that you can adjust to try help this. (You might just have to stop/start recording around the static on the tape, sadly)
Perhaps one of these ideas may help... Good luck with it!
("Hope That Helps!") ~ Troy