What happens when a wicket goes down

As soon as a wicket falls the ball is dead and whatever happens until the next ball is bowled will not be accounted for. We can take an example where a batsman gets by giving a catch, at the same time the fieldsman see that the other batsman is out of the crease tries to run him out, but this is not valid. Once the catch is taken clean the ball is dead and nothing else counts until the next ball is bowled. As a matter of fact, even two run outs also cannot happen, see this funny video http://iravaiiravai.blogspot.com/2007/10/best-cricket-runout-2-runouts-in-1-ball.html
The second runout is not valid, only the first one is counted. I think Lankan's attempted the 2nd Run Out as keeper thought that first one was a close call, so he throwed the ball to other end, just to make sure..

Also, a rule of Run Out which umpires look out for is when there is a confusion of who has to go, the rule of thumb is whether they have crossed each other or not, it means once they cross over there is no chance to do a sacrifice for the sake of the other, I can remember one idiotic situation where Pak was playing against aussies and the batsman were Inzamam and Salim Malik(not sure exactly though) both batsman were reluctant to go, so the umpires called the third umpires to decide, even 3rd umpire has to several replays to decided how they crossed over and who has to be declared out...Just for a thought..