Lebanon has been a Syrian colony for about 30 years. They control much of the politics there, pitting the many tribes and factions in a complex tribal and multi-religious society against one another at the cost of thousands of lives and the destruction of the nations considerable pre-civil war wealth. The Syrian military is taking its eye off the ball in Lebanon trying to save their asses at home. Lebanon is now receiving a wave of refugees out of Syria. Many run to relatives in Lebanon, into these ethnic enclaves they arrive with stories of butchery they escaped, it's too much, the pot is boiling over with old grudges from the past civil wars.
Most news firms are not covering this, but it is spinning out of control, some towns are in full scale fights neighborhood against neighborhood or one town against another, it breaks down by who helped the Syrians, who prospered from it, past atrocities and thefts of property, the scabs from the old civil wars are ripped off, again.
This may benefit Israel initially if the various factions use up some of their weapons, and which groups prevail will determine the long term benefit or risk.