That is just inexcusable.
If I were the coach, I'd probably bench that guy for an entire week so that he and the rest of the defense never pull some shit like that again.
Jaylon Smith almost made a similar mistake vs Houston on that great play where he simply threw his shoulder into Watson as opposed of wrapping him up. In fact, the reason Watson didn't bounce off of that hit and fall into the endzone is because there were 2 more defenders there.
My point is, why the hell is it so hard for defenders in football today to wrap a guy up and take him to the ground? You can still lay people out while wrapping up, so I don't know what the excuse is.
And this jackass in the video tries to grab him and throw him forward?
If I were a HC or even a DC, I would play one stupid tackle attempt every single week for my players to remind them why they need to secure the tackle because shit like that is inexcusable.