Isn't that technically an act of war?
If you are looking for an excuse to start a war, you could call it that.
It is certainly an armed act, or an aggressive act, but most politicians are careful about so labeling minor clashes like this.
If one were a Georgian politician, one could make that case that this was an act of aggression (to use a common UN term) but since no state of war exists, it might be precipitous for the Georgian to call it an act of war.
See the ramming of the US P-3 about six years ago by a Chinese Fighter. (Actually, it was a case of a fighter pilot screwing off and screwing up) There is no question that the Chinese fighter was on an intercept mission, and ended up by its actions hitting the P-3.
It could have been construed as an act of war over international airspace, but it was not. It was more or less a "regrettable incident," as was the downing of the Airbus over the Persian Gulf by the USS Vincennes. Even so, much political hay was made of it.
The two governments in the Vincennes incident, in Iran and in the US, correctly deciphered it as a cock up, not as a deliberate act of aggression, even though at the time the two nations were shooting at each other now and again in the Persian Gulf.
If the Georgians are taking the position that the Russians violated their airspace with an armed military jet, that too can be construed as a warlike act, but to call it an act of war seems a bit much.
Back in 2004, there was a reported incursion into the Iranian western ADIZ by a couple of American fighters and their tanker, while refueling and dodging some thunderstorms. It resulted in multiple warnings from Iranian air defense. IIRC, Rummy was on the air apologizing for the screw up within 24 hours, and the Iranians did not classify it as an act of war. They seemed to be content with the apology.
I'll admit, the video presented, it if is genuine, does not support "inadvertent" as a descriptive for the jet's actions.
DR