It can be watched free with TourTracker.com.  Just enter your name and email at http://thetourtracker.com/ then click on the apps tab and select download the app and select USA Pro Challenge for your phone or web.

They claim to be covering the Vuelta.

From: Bike-racers [mailto:bike-racers-bounces@mailman.swcp.com] On Behalf Of Craig M. Doolittle via Bike-racers
Sent: Saturday, August 15, 2015 1:59 PM
To: bike-racers@swcp.com
Subject: [NMCycling] USA Pro Challenge TV Coverage?????

Is there any way to watch/record the USA Pro Challenge on Comcast?

It appears to be on the Universal Sports Network, which is not carried by Comcast L

Thanks

Craig