A MEASURING TOOL RATHER THER THAN ACTUAL EYES ON YOUR CONTENT
Reach is not the number of people who saw your content. It's not the number of people who engaged with your content. It's the number of people who could have seen it if they were focused on a specific part of the page at a specific time.Measuring Reach is an inexact and inflated measure of how many people actually saw something, in a way reach is an "imaginary stat". The only real use of looking at the reach of a post is to measure how far something may have gone, compared to your other facebook posts" .A more accurate gauge as to whether people are seeing and enjoying your content is whether they have reacted to it, commented on it or shared it, or, if the campaign in question was supposed to be creating leads, sales or directing traffic to a certain place, then you can track that very accurately on your website and see whether there's a tangible effect.
The example above shows that from a reach of 3,366 only 1,154 users had the video on their screen for more than 3 seconds, which is less than half the number of people suggested by the reach stat. The drop off rate after three seconds for video playback is very steep - so it goes to show you that the reach metric really is just a general gauge as to how far a post went compared to other posts on Facebook, it should never be mistaken for people actually seeing your content.