Major League Baseball commissioner Rob Manfred and National Basketball Association commissioner Adam Silver voiced their support for regulating fantasy-sports websites FanDuel and DraftKings in a joint appearance at CES on Thursday morning.

Citing the mounting legal challenges faced by these fast-growing businesses, the commissioners noted they were monitoring fantasy sports very closely and that they were an important source of fan engagement.

“I feel it should be regulated,” Silver told TNT sportscaster Ernie Johnson in a Q&A alongside Manfred at a Turner Sports-hosted forum on the sports business. “It’s a healhty form of entertainment.”

“I also agree with him that it’s important that this industry has transparnecy and appropriate regulation,” echoed Manfred, who noted MLB’s partnership with DraftKings. NBA is more closely allied with FanDuel.

Both businesses have been hobbled by legal challenges in New York and Illinois, where state attorney generals have filed lawsuits characterizing them as illegal sports-betting operations.

“It’s frankly a lot healthier than the alternative, which is illegal sports betting,” said Silver, who added that he believed fantasy sports should be regulated at the federal level. He also echoed New Jersey Gov. Chris Christie’s contention that fantasy sports could become an important revenue generator for states when taxes are applied.

The commissioners put fantasy sports in the context of a broader discussion about how various new media are important tools for getting new generations of fans engaged in their leagues’ activities. But that poses myriad challenges to businesses struggling to keep up with the rapid pace of change. As Turner president David Levy said at the opening of the morning-long set of panel discussions, “Every deal is highly complex involving all screens and maybe even some platforms we don’t know about in 2016.”

Also on tap at the Turner Sports event is a showcase for a new e-sports league the Time Warner division is about to launch with WME/IMG and a live telecast of “Inside the NBA,” which relocated to Las Vegas for the day.