that's the cable but are you sure you need 50ft? Run some string to check distance.
because the CL2 (plenum fire rating) only go 25ft.
The other option is a HDMI to RJ45 extender which is now being made.
I've run 75' VGA cables from monoprice and they were amazingly clear.. with a 50' VGA to RGB that looked stunning.
I haven't found any prices anywhere near this for this type of quality. There are tons of threads on AVSFORUM about their cables also.