What type of analogue video signal?
Cat5 is not shielded it's twisted pair to help reject noise since it usually carries digital signals a little noise isn't an issue. RCA terminated wires are usually shielded. The RG6 works fine here.
Cat5 can be used for all kinds of signals with the use of a balun.
Here is an example. I have used baluns to run vga signals over long distances where a vga cable was impractical.
Basically, I would say no, the Cat5 is not well suited.
Wait for some more answers because someone will correct me if I'm wrong.