Poker works really well with video content so .tv is a natural fit for poker terms :imho:
Think of all the poker shows on TV just now & all the live streams or classic poker clips available online, makes natural sense to put this video content online and surround it with affiliate links that will make you $25 - $50 is any user joins an online poker site.
I tried very hard to get a collection of Poker/Gambling related .tv's last year but even then all the domains i wanted had been taken for a while, all i managed to get was 'ChannelPoker.tv' which i'm not too keen on.
I am shocked to see 'PokerNightLive.tv sold for $3,500' as i had never heard of that one before, to get that price for a 3 word .tv is a one off though.