I have used many times MG995 or MG996 and SG90 with 7.4V (2S) Lipo battery with no issue.
But, there is a but, I burned a lot of servos, without knowing the reason.
I think that when a servo is blocked, whatever the voltage, if the intensity increases, there is a moment where things end badly.
About the video, with short, it seems not possible to show it on the forum.