Video input switcher for DVD and other sources

I own several pieces of video, including two VCRs, one DVD player and soon another DVD player. I have noticed that DVD players often show a very strange distortion, the picturing distording, going dark/light, which I suspect of being Macrovision or some sort of protective device connected to another input and then, from this other device(typically a VCR) to a direct video input. Any help with recommendations will be greatly appreciated.
Extron makes the best video switchers period.

You can frequently find them used very cheap on eBay, or pay the astronomical price out though, there are MANY different models, so be careful and get the one you need. You won't regret it!
The DVDO is a good switcher that upscales everything to 480p and doesn't cost a great deal.