This is what happens my end:  First click plays briefly then stops, second click it works perfectly.
This is on a MAC.

https://youtu.be/gg7SerQj4hQ

No change John just a .3 sec play which is less than satisfying!
Repeated clicks simply repeat the 0.3 secs.
All else works in other areas of Mac etc.
Restart changes nothing, but Im guessing it's a problem "up my end". 
Most things are.
Ignore me- its praps for the best,,,,

They only play for a brief moment with me, but click on them again and they play normally.  I'm also using a Mac.

Play fine here also.  Is it just these particular ones or do any of the others I've posted work?   It could be a local issue - worth trying again later.

They play fine for me.
I can even play them all at once !!

Hy John, Each video only plays for 1/2 sec (for me). 
Ive restarted my Mac but it still wont play your Vids. 
Do they play for you on your computer, or is it me!?