The key is to figure out the pattern, but unfortunately that's not always easy to do. For a false switch indication to occur, three other switches need to be closed at the same time. While that initially sounds unlikely keep in mind any switches that are normally closed or frequently closed (ball trough, ball lock, drop targets etc.). I would go through the video and see if you can spot the pattern of which three switches are closed when the problem occurs. If that doesn't work you can start closing a combination of switches while in test keeping the following in mind.

One of the switches will be in the same row as the playfield tilt and one in the same column as the playfield tilt. The fourth switch when combined with the other two will form a rectangle on the switch matrix. One of those three switches will be the problem.

More info:

http://pinballrehab.com/1-articles/solid-state-repair/repair-guides/146-switch-matrix-theory-and-troubleshooting