Elgato earned the nickname "Elcrapo". Most of your exposure problems may actually be here, as the card is known for it. Same for Easycap/EZcap, which again earned the nickname "Easycrap".
Another card is suggested. Which card depends on OS. Which OS are you using? WinXP/7 is best, but others can work. Mac/Linux are the worst capture systems, few options, especially on latest OS versions.
Always use
VirtualDub, nothing else, for the USB cards.
Not VirtualDub2, as it captures different than
VirtualDub (sometimes good, usually bad).
Standard workflow is
VCR > TBC > capture card
Not just any VCR/TBC/card, but specific models known for quality.
VHS VCRs are made with cheap internals. The image is almost always more unstable, has more visual boogers like wavy/wiggly picture (sometimes slight, sometimes like ripples in a pond, but always distracting). Cheap consumer VHS VCRs also tend to oversharpen, over/underexpose. The S-VHS VCR will better play tapes, due to better transport and s-video. More accurate color and sharpness. The line-TBC models will remove color noise, most/all the wiggling, etc. JVC calls it "DigiPure", and its apropos, as it purifies the image quality. It makes a big difference.
You will require some form of TBC, be it a minimalist TBC(ish) ES10/15 (a shortcut with a fail rate), or a combo of ES10/15+DVK, or an actual TBC. The solution chosen it determined by tapes and budget.
Consumer camcorder optics weren't great, so DV 720x480 is more hopeful thinking than anything else. The true resolve probably doesn't exceed s-video by much, or at all. You can capture DV over analog, but only do it after getting a good card. often actually prefer DV over analog, as the digital transfer "capture" can be a PITA. The biggest problem is the blankout and lag between clips. DV transfer can clip some seconds, whereas analog will acquire every second played. With good camera work, not an issue, but what consumer used good camera work? A clip may immediately start with the words "HAPPY 100th BIRTHDAY GRANDMA!", and you'd probably miss it on the digital "capture", but not the analog capture.
Remember to look in the marketplace subforum:
http://www.digitalFAQ.com/forum/marketplace/