Is it ok to run CAT-6, Coaxal, and HDMI near hot water pipes
It would be a good idea to keep them as insulated from heat as possible. Depending on the type of cable, they could potentially release toxic fumes if they are exposed to too much heat.

Generally, if you are running them near a hydronic heating system, then the pipes won't get hot enough to melt the jackets of the wires as long as you wrap the pipes in foam insulation. This insulation can be found at most home and hardware stores and varies in size. It may also help the efficiency of your heating system by reducing the amount of heat loss in the pipe in areas where you don't want to heat.

You may want to do further research to see what the wires are rated for. I found a guide to in-wall wire installation that may help you out.

In wall cable ratings