Sportsnet had the footage:
Cernak discussed the incident after the game, per USA Today's Mike Brehm: "He kicked me when he was on the ice. I think he was a little mad at me."
Diana C. Nearhos of the Tampa Bay Times provided some context for the incident:
"Cernak was sitting on Kassian and fellow winger Josh Archibald, which should have been an interference penalty, but is a common move to keep someone (in this case someones) out of the play. Kassian pushed himself free and then aimed the kick at Cernak to get him off Archibald.
"The play started when Kassian grabbed onto Cernak. Archibald lost his footing and barreled into the pair, upending them. Cernak stayed on top of the pile for an extra few seconds.
"A linesman came up behind the play to break up the trio, but only a referee can call a penalty. Both referees were away from that pile watching the puck in play."
As noted by Mike Stevens of Yahoo Sports Canada, Kassian has made the news recently for physical confrontations, most notably jumping the Calgary Flames' Matthew Tkachuk in January. He was suspended two games.
As for Thursday's matchup, Kassian did not receive any punishment for his actions at the time, and he finished out his team's 3-1 road loss to Tampa Bay.
However, Nearhos noted that the NHL's Department of Player Safety could be giving a call to Kassian about the act, with TSN's Darren Dreger tweeting that it "would be hard" to believe that such a conversation won't occur.