They correctly understood that this proposed resolution was not a way to peace in Syria, but a devious step towards foreign military intervention and regime change to suit foreign imperialist powers, not the Syrian people.
In my opinion, they acted correctly. They were tricked over Libya, but hopefully they will stand firm over Syria and Iran. We should support Russia and China on this, despite the scurrilous campaign against them by corrupted politicians and mass media from the West/Gulf states, which have their own agendas.
Since 1970 the U.S. has used its veto 79 times, with more than 40 related to issues in the Middle East. The majority have been resolutions that have criticized the Israeli government.
It used its last Israeli veto to block a resolution that would correctly term Israeli settlement activity in Palestinian territory "illegal" and demand a halt to all such actions.
U.S. Vetoes of UN Resolutions Critical of Israel - (1972-2011):