I don't see anywhere that you say which software you used to capture from the various devices you name. In fact, I got the impression, since you want VS to work, that you are trying to use VS as the capture software, as well as then editing the captured video. If that is the case -- and please post if you are not doing this -- then it is the wrong way. We *always* recommend that you use the software which came with the capture device to capture. It is specially made for the device. And often, the manufacturers of the hardware refuse to share their secrets with software makers like Corel. So VS will not necessarily work, or work well, with different capture devices.
Your Ads device is a case in point. Normally, that comes with an excellent piece of software called CapWiz. It always works perfectly with the Ads devices, and then, when captured, the video will open in whatever version of VS you have and is successfully edited in it.
Personally, when trying to capture from an older 8mm camcorder or even an old VCR, I use a Sony Digital 8 camcorder which can be connected to the source via firewire; or will even play the analogue 8mm tape directly. You capture in DV format via firewire, and the quality is as good as it will ever get. Or you can do the same thing with a DV capture device, such as one of the Pinnacle ones, though they are a bit expensive.
But failing that, a decent USB device, capturing with its own software, will usually do a good job too.