This video talks about how an "observer" can alter quantum mechanics. A measuring device caused electrons to behave differently simply because it was observing their actions. They no longer behaved like waves, but traveled in straight lines.
The experiment
Electrons were fired one a time through a double slit yielding an interference pattern similar to a wave. The results showed that the electron left their device as a particle, became a wave of probabilities, went through both slits, neither slit, and each slit separately. These mathematical formulas didn't make much sense to scientists, so they built a measuring device to try and see which slit it went through. While using the new measuring device the electrons stopped creating the interference pattern, and instead traveled in straight paths like photons. The act of observing the electrons collapsed the wave function.
How does this relate to multiple realities?
The act of observing something collapses the probabilities...
I think that when things are outside of someones observations they are in a state of flux. When they are observed again the multiple probable realities are experienced by alternate selves. Each version of you will experience one of these probable realities. Multiple realities are diverging all the time related to your spontaneous thoughts and feelings. I think if you pay attention to your thoughts and feelings you will understand the daily events you experience.
Example of alternate realities
When you go to the store there are a lot of alternate realities you could experience:
All of these alternate realities happen to different versions of you each time you go to the store. The secret is learning how to increase the probability of experiencing desirable realities.
How to increase the chances of experiencing desirable realities
Your thoughts and feelings determine which realities you experience. Thoughts are extremely powerful, yet so many people take them for granted. People spend a huge a amount of time thinking and feeling. Your thoughts have their own magnetic properties, they attract and rappel things to you. They attract and rappel events, and "random" things that seem to happen to you, things like friends calling, people coming over, running into people you know, coincidences, and pretty much all events. To increase the chances of experiencing positive events you should use your imagination; try to imagine what you would like to experience, use planning, visualization, be creative, try to be optimistic, get good sleep, doing small symbolic actions that relate to your goals is very important.