This is a subject that chills web video companies and customers — especially the day after Verizon Wireless announced that it will eliminate its unlimited data subscriptions for 4G customers. Comcast, the No. 1 broadband provider, said in a blog post that it’s “time to begin to move to a new plan” for its Internet service. As you might expect, the post clearly describes changes consumers might like, including one that raises the residential usage cap to 300 gigabytes a month from 250 GB. But the post is vague about potentially unpopular changes — leaving open the possibility that Comcast might dramatically raise the price users pay if they exceed the cap. Comcast says it must “address the realities of managing a network that services more than 20 million customers.” But Internet activists fear that a hefty new fee could deter consumers from subscribing to rival services such as Netflix which use a lot of bandwidth to stream movies and TV shows. The possible change “illustrates that Comcast is really trying to discourage subscribers from experimenting with online video alternatives,” Free Press Policy Adviser Joel Kelsey says. “We call on Comcast to drop the caps and these exorbitant overage fees entirely.”

Comcast is positioning the change, including the higher monthly usage cap, as an improvement for consumers. It says that it’s responding to protests over its initiative offering unlimited VOD to Xfinity cable customers who use an Xbox 360 in place of a cable set top box. Critics say that gives Comcast a big advantage over online rivals that are subject to the usage cap. The company counters that VOD is part of its cable video service and doesn’t travel over the Internet. Comcast’s blog promises that it “will be transparent to our customers” as it weighs options, and will provide them with “the tools necessary to manage their use of our high-speed Internet service.”