Squib loads are not very common with modern factory loaded ammunition, and are typically the result of reloads or military surplus ammunition.
A woman, her shooting partner, and their cameraperson are lucky to be alive. Her M1 Garand detonated after she failed to check the barrel for an obstruction due to an apparent squib round, and she attempted to fire another shot.
Both shooters are firing their Garands when there is an apparent lack of recoil when she fires at 00:12 into the video. She is obviously aware that something is amiss and seems to check the chamber, but does not unload the rifle to check for the presence of a barrel obstruction.
She raises the rifle and fires it again, causing a catastrophic weapon failure. Parts of the weapon fly in all directions.