So it's unlikely you can connect coax from Comcast today. There are many web pages on that so I'll stop here.

But then you put your cable box through a VCR so that's a mess. I would not be able to tell if you had old Standard Definition through that or how to wire that up. Let's just say that's a mess without any easy answer as I don't see the VCR. Most are old analog and would connect with the usual red white yellow RCA to the TV and then you select the composite (not component) input on the TV.

"I've spent a couple hours trying everything I can think of and have had no luck getting a single channel. Everything says weak or scrambled signal."

If this was on COAX, that was expected. Here's a web link about the change.
http://www.engadget.com/2013/04/15/comcast-encrypt-basic-cable/

That was 2013 and now it's 2015. Welcome to the machine.
Bob