I wouldn't recommend using phone wire for video cable. Instead buy Cat 5 cable from Frys or wherever.

Phone cable is typically Cat 3, which is not twisted pair strands and Cat 5 is twisted pair. Should make a difference for video that is much higher bandwidth than audio, but will probably also make a difference with audio as well as the twisted pairs help to eliminate crosstalk and other types of interference.

I wouldn't recommend making your own video cables, however, unless you have access to Canare connectors and your own termination kit. Stuff from BlueJeansCable.com is really solid, works great and doesn't cost an arm and a leg.

As you can tell, I'm pretty much totally sold on their stuff and their way of doing business. All cables are hand cut to specification and hand terminated with industrial quality connectors. Only cable types they don't offer are fiber optic.

Some of the other cable manufacturers offer decent cables as well, but the Canare RCA connectors are seriously like butta, seriously.

My $.02