Obviously the first 3 1/2 minutes already has happened as that was all news footage, the tricky part is what comes next.
So BO calls for Martial law, (Does he have the balls, that would cost him his power base of blacks) part of that is the suspension of Congress, , will they obey ? If they don't then right there you have a split in the chain of command that will lead to Civil war or forced removal of the Pres. That is the key question. The second question would be the purpose and scope of the order, if it were to squash riots by unpaid welfare recipients and illegals, or to suppress Tea party protests by fed up citizens. The answer to THAT question has important ramifications in the response by military and police forces, if it's to quell rioting they will go in and kick ass just like always. However if the order is to mobilize against peaceful protesters, reserve and guard members will be choosing between their oath and their orders, units will follow the lead of their commanders, some will follow orders just like in Shays rebellion, the whiskey rebellion and Waco Some will not involve themselves, whether they just drag their feet or refuse to move, others may try to protect the Citizens.
UN intervention ? We supply most of their equipment and lift capability, unless they find some one else to supply heavy equipment and get them and it here it will not happen, IF they overcome that, they can of course stage through Canada and Mexico, 90% of the population will do nothing, the other 10% are divided between Thugs hoodlums gangbangers and other scum, and "The resistance". Win lose or draw it will be long and bloody.