We have become a nation of streamers.

Web-traffic tracker comScore (Nasdaq: SCOR) has issued online video consumption metrics for April, and the report shows that we've been busy with the clicks.

In the U.S., 178 million Internet users -- more than half the country -- streamed a video in April, according to comScore Video Metrix. As a nation, we took in 30.3 billion videos, a lot more than the 16.8 billion clips we consumed a year earlier.

Google's (Nasdaq: GOOG) YouTube led the way, naturally. It has even tacked on market share over the past year, going from a thick 40.7% slice of the pie to an even larger 43.2% chunk. YouTube's penetration may not seem like much, but it translates into a 93% surge in the number of videos being served.

YouTube owns this space. Hulu, owned by a consortium of media giants, is a distant runner-up, with a 3.2% sliver of the market.

News Corp.'s (Nasdaq: NWS)(Nasdaq: NWSA) Fox Interactive is the only major player to have served up fewer video clips this April than it did a year earlier, yet another troubling indication as to how far MySpace has fallen.

Outside News Corp., everyone's a winner regardless of market-share jockeying, because they're all attracting larger audiences. Even online-advertising laggard AOL (NYSE: AOL) managed to nearly double its clip viewership.

Are you ready for the bad news? Well, our lazy, eye-candy-seeking pursuits have to be leaving other industries smarting. If we took the time to collectively watch 80% more videos than we did a year earlier, where did that time come from?

I ruffled some feathers last month, when I suggested that the success of Google, Apple (Nasdaq: AAPL), and Facebook in delivering free -- or nearly free -- entertainment was killing America. It was intended in a tongue-in-cheek spirit, but the reality is that time checking out YouTube, playing free App Store programs, or tending to faux farms consists of ticks on the clock that aren't being spent elsewhere.

Google will lead the way in selling ad space against our sticky viewing habits, but there are entire leisure industries that may crater as we the consumers reallocate our leisure time.

There's plenty of meat in comScore's trend report, but the heartiest nugget is the unspoken reality that Web-based video is growing at something else's expense.  

Is Web-based video a friend or foe? Share your thoughts in the comments box below.