I pretty sure that's not how it works. The NHL gets paid by the network to air the games and the networks recoup cost by selling commercial time. I don't know if there's anything in the contract that adjusts for OT, but it's doubtful. BTW, I definitely remember commercials during both OT periods on NBC Sports Washington. OK, I just went back on my DVR to make sure.
They only do commercials in OT for the playoffs between periods, or at the halfway mark or closest whistle they sometimes do as well to clean the ice.
The NHL doesn't get paid per game. It's a contract, with a TV network. The network pays to get the rights to air the NHL for however many seasons the contract is lasting for depending on where they are airing. TSN in Canada for example has been losing the number of NHL games despite bidding on more every season. However the OT thing is just an example of the type of things that are included in the contracts.
However it isn't the Network that gets all ad revenue. Depends on the ad. 90% of sports ads that air on major networks are all for products that partner with the NHL. Which means the NHL gets money for showcasing their products, again likely done on a contract.
None of this really plays an effect on the OT though, since it's not a case of the NHL wanting to give us the action more frequently. It really is they alloted X time for the game, and want to get it done as quickly as possible. The more breaks there are in OT the more rests the players get, the longer the game could potentially go. Forced repeated play makes it far more likely for someone to make a mistake and put the puck in.
The regular season is different since the games are traditionally alloted extra time for OT and the shootout if it goes to it. But you'll notice the break in between the first and second and second and third, is always longer than the break between OT and the shootout, even in the regular season. This is for the same reason. Networks may pay the NHL for their programming, but it's ultimately the networks discretion what they air. I've seen countless times before I had Gamecenter where the TV station in question popped over to the news or Friends or whatever. This often happens in other less popular sports if two unpopular teams are playing. A lot of Networks get away with this by having "sister networks" or as you may be more familiair ESPN 2, 3, etc. They sometimes move games around those channels if scheduling conflicts occur or if a game is perceived to be not "noteworthy" enough to dominate main channel time.
