[Steve Van Doorn]

Many of the video's you can hear what you're calling Echo's and shots from the weapon. Sometimes the "echo's" come come in before the shots fired.

They also have a different firing count.

That isn't even logical. It can't be an echo.

On top of that the taxi driver when the video first starts you can hear shots and the echo. From that you can hear what the echo's sound like.

Here is an example of one video:
https://vid.me/BbmlX
At 13:30 and 18:50 absolutely no doubt what so ever there were two shooters

One is far away(hotel) the second is very close (near parking lot)

You might want to back up the first time stamp a bit.
That way you can clearly make out the have no similar pattern.

[HLPhat]

>>13:30 and 18:50
>>One is far away(hotel) the second is very close (near parking lot)

In both of those instances there are two distinct patterns of sound events:

1. The local snap of the bullet passing/impacting. (very close)
2. The muzzle report. (far away)

https://vid.me/BbmlX