Comcast is disputing a March study from research firm NPD Group that concluded Netflix dominates the video-on-demand market, reports Multichannel News.

The study said Netflix had a 61% share between January and February 2011, followed by Comcast at 8%. But Comcast said that the research firm tracked all of Netflix’s streaming service, but only included shows from cable or other pay-TV services for which an additional fee was charged.

Comcast said that if views for all of its free and premium movies were included, Comcast would have had a 54% share of movie viewing, compared with 31% for Netflix in Comcast’s markets, the article notes.