According to researchers at SNL Kagan, the multichannel video entertainment market, which basically has grown in virtually unbroken fashion for decades, appears to have suffered its first-ever decline in the second quarter of 2010.

There was some continued shift of market share from cable and towards satellite and telco providers. But those shifts also were accompanied by an apparent net loss of 216,000 subscribers in the multichannel marketplace as a whole, compared to a gain of 378,000 in the second quarter of 2009.

Observers who have been watching what has been happening in some other legacy businesses, especially fixed-line voice services, are familiar with similar processes: gains for competitors and losses for the top incumbents. But there is more at work that market share gains and losses. Over the last decade, the total number of customers available for anybody to get has been dropping. 

"Cable TV" has been a mature market for some time, but still has managed to eke out small gains, year after year, despite gains by satellite and telco competitors. But that appears to have hit a possible inflection point in the second quarter. More data, over more time, will be needed to confirm the possible trend, but it would be a historic watershed if the market actually shrank for the first time. 

Cable was down a combined 711,000 subscribers, with six of eight top cable companies recording their worst losses ever. By contrast, satellite providers added a combined 81,000 subs and telcos netted 414,000.

Cable's combined share of the market was down to 61 percent from 63.6 percent in the second quarter of 2009. 

Telcos now claim six percent of the video market, up from 4.3 percent year over year. It is tough at this point to figure out how much the economy and moribund housing market had to do with the results. Both those trends would normally be expected to slow the market.

But most observers also are watching for signs that alternative channels, ranging from online video to DVD rentals, are having an effect as well. So far, there has been scant evidence of any significant shift of viewing habits. 

Some people, for all sorts of reasons, seem willing to live without paying for cable, satellite or telco-provided multichannel video entertainment. But most people appear not to see the advantage of cord cutting. 

The hassle factor likely is one reason, but the biggest reason is that it is not yet possible to replicate the value of a multichannel video subscription any other way. Live, high quality content, for example, is tough to find. 

Most other instances of product substitution involve products that provide equivalent or even better value than the products they displace. Mobile phone service is probably the best current example. Given all the things a user can do with a smartphone, it simply is a better product than a typical voice landline. 

But even if it were possible to replicate the content access people normally expect from a multichannel video subscription, there is still the ease of use factor. Still, just about everybody is watching for some sign that consumer appetites and supplier willingness align in new ways. 

Right now, there is no way to tell whether any significant number of multichannel video subscribers would drop those services for an alternative, precisely because such an alternative does not exist.

Plenty of people, mostly young adults, say they have abandoned multichannel video for good. But those examples still are relatively rare. We won't really know for some time what the actual state of demand is for alternatives to multichannel video services, if only because suppliers will not provide it, while the inconvenience and lack of compelling content make the alternatives less compelling. 

But negative growth is a first, and sets up a growing expectation that something is going to change, sooner or later.