Yes that’s Neville Longbottom slashing the head of Nagini using the Sword of Gryffindor. Nice cartoons uh?
That’s actually a screen-cap from “How Harry Potter Should Have Ended” video which i found on Youtube. The short animation tells about certain spells and potions that could have saved some characters, and might have stopped Tom Riddle from becoming Lord Voldemort.
The video looks fun, but for some reason, i find it true and rational (though J.K. Rowlings always have reasons for everything. And if it will be followed, the entire Harry Potter entire might just fit into a booklet). Check it for yourself!