Video over IP is an option and CAT5 is cheaper than the precision coax we are talking about. But the equipment/balums/converters used in various systems can quickly bring the cost up to or above the coax approach.
That is a good point and one I forgot. I know that I am using the cable when I run it, so I run the cheapest method at the time. For component cables that is the mini precision coaxial cable. The alternative is to run plenty of Cat5e wire and run baluns for any signals you need. The baluns have a big price range depending on what signals you are trying to convert, but an average might be about $100/pair. That made it more costly in my situation, but you might want to really explore this option yourself. If you know that 80% of the cable run isn't going to be used for a while, then running cat5e is probably better. If you know there are locations where you will use the wire right away, using the correct wire without baluns is probably more cost effective.
As CollinR mentioned, running cat5e wire will also allow you to "future proof" as much as possible because hopefully there will be baluns made for future needs. This is one reason that I ran 2 cat5e wires in addition to the precision coax to every location. Actually I ran at least 2 cat5e wires to every drop I made, regardless of initial purpose of the drop. I agree that it is impossible to run too much cat5e wire, but it is easy to find out that you didn't run enough. So definitely run more than you think you need.