There is no danger of the glass shattering as long as you make the flame guard a couple of inches larger than the burner pan. The flame guard should sit outside the burner pan by a minimum of 2" on each side. This keeps the flame from directly contacting the glass which can cause it to break or leave soot/residue on the glass. The glass also doesn't shatter also because it heats through slowly as it heats from the flame - there is no instant temperature change which can breakage in glass (i.e. pouring cold water on a piece of hot tempered glass).
How tall is the glass in the beginning of this video please?
The glass is 6" tall. It looks taller because that's one of our smaller burner pans (18" x 6").
Is there a danger of 5/16 thick glass shattering because of big temperature difference between side near flame and side away from flame?
There is no danger of the glass shattering as long as you make the flame guard a couple of inches larger than the burner pan. The flame guard should sit outside the burner pan by a minimum of 2" on each side. This keeps the flame from directly contacting the glass which can cause it to break or leave soot/residue on the glass. The glass also doesn't shatter also because it heats through slowly as it heats from the flame - there is no instant temperature change which can breakage in glass (i.e. pouring cold water on a piece of hot tempered glass).