A PBS Genetic Genealogy Special/ +Are a bunch of shared small segments meaningful?

A PBS pledge drive special featuring a genetic genealogist that all of those in the genetic genealogy community have been following for years and is well known to us has been airing on PBS. Diahan Southard hosted this PBS special called "Your DNA Secrets Revealed". It features people who took DNA tests and found unexpected, surprising, health, relationship, or ethnicity results. Some of those participating in this show are also well known to those in the genetic genealogy community such as Jerome Narramore. Hopefully Diahan's enthusiasm about DNA testing encouraged people to donate to PBS, so they might sponsor more shows like this, and motivate more people to consider testing. I have noticed a drop off in the number of matches my family has been getting and would love to see more people test. 

What could a bunch of small segments shared mean? 

Every once in a while, looking at shared segments in chromosome browsers, I've discovered 5 or 6 small shared segments and wondered what the relationship with this match could be? I had heard that the more segments you share with someone the greater the likelihood the match is close as opposed to one large segment. 

There are several reasons why we might share a number of segments with a match including:

1. Endogamy, caused by ancestors who exclusively married within a small religious group or population group. 
2. Being related to a match more than once. 
3. False positive segments.
4. A close family relationship to your match. 

I'm finding matches that share 5 or 6 segments with me are close family. At least 2nd or 3rd cousin range. 

How do DNA companies define close relatives? The DNA testing companies generally place first cousins under close relatives, and sometimes 2nd cousins.  Aunts and Uncles are also under close family. Extended family generally includes 2nd and 3rd cousins. The rest are under distant cousins. 

When I first saw a particular match, illustration below, in the chromosome browser I didn't know what our relationship was? Some of the segments are small and could have been false positive segments? The largest is 20 cMs. 

Could be a close cousin or a more distant cousin? My paternal aunt's results answered this question. She shares 16 larger segments with this shared match. 

I contacted this match and found out exactly how we are related. This family lives in Austria and I had an idea of how we were related but not on which line until I heard from his nephew. This tester was a 1rst cousin once removed of my aunt. This family had photos of our family we didn't have. One of our best cousin finds. 

Not  long ago this Austrian family uploaded their MyHeritage kits to FamilyTree DNA. I discovered one of my first cousins at FTDNA shared even more DNA with this match than my aunt. My cousin shares 533 cMs with this match and my aunt 450 cMs. 

Why do I only share 90 cMs with this same match? Looking at my Genome Mate Pro segment map. I see that I inherited DNA from my grandmother's French Canadian family instead of my Austrian family like my aunt and cousin on some of those segments.

Four generations of our Austrian extended family have tested. Since I didn't share as many large DNA segments with the eldest member of the family, the uncle, I don't match with other members of this family. My cousin and aunt match all 4 generations. My first cousin is my aunt's nephew, not a child of hers, so he inherited his segments from his father, my uncle. They both match four generations of this family.

The uncle shared 16 segments with my aunt, but only 3 segments with his great-great-niece. 

A number of small segments can definitely be meaningful and, as in this case, the match is a member of our extended family. As we can see it's important to test older members of the family because younger members may not share enough DNA to show up in our results. Also testing as many family members as you can afford is very helpful because we all share different segments of DNA.