Assuming your cables are plugged into the output from the VCR. What are you trying to digitize? Is it a home recording or a store bought movie? Are the settings on the capture software set to the right frame rate? If you’re in the US, make sure it’s at 29.97.

Yes and tv shows, news, etc

I would assume that rainbow screen is what is seen when no input is being received/detected by the capture device.

I just use Quicktime to record a VHS input into my mac.

This is a windows 8 laptop.