Although growing strongly, online and mobile video have not harmed overall TV viewing time, and all types of video viewing continue to rise, according to a Nielsen Online study conducted in May.

An average U.S. television viewer watched more than 127 hours of television and spent more than 26 hours online in May, according to the survey, eMarketer reported.

On the other hand, online video viewers watched two hours and 19 minutes during the month on average, and mobile video viewers watched videos for an average of three hours and 15 minutes on their handsets.

"Commercial television is alive and well - growing one percent year over year - despite the rapid adoption of other platforms," John Burbank, chief marketing officer at Nielsen, said in a statement.

The study also found that viewing habits vary by age. Mobile video viewers skewed to younger generations, while TV and online video viewing spread much more equally across age groups, eMarketer reported.

According to another study conducted by TNS Global last year, online video viewers are watching less TV than before. Of those who watched less TV than the previous year, 35 percent said it was due to spending more time on the Internet.

It seems that video viewing on one medium can potentially damage total viewing on another. However, according to eMarketer, it was not true in the aggregate because overall viewing time keeps going up, as well as the total number of viewers. The number of TV and online video viewers in U.S. is expected to rise throughout 2012, when more than 300 million are expected to watch TV and 190 million are predicted watch online video, according to the report.