Nearly every defensive secondary player tackles low. They don't have the size or strength that DLs or LBs have. Watch our secondary from last night coming up and stopping the run. If this USU guy has the wherewithall to think "I'm going to injure this guy on this play" and then is able to execute on that thought in about .001 seconds, he is a marvel. He made a football tackle and it just happened that Taysom was planted his left leg right at impact. The defenders head is looking at the ground.
Defender engages Taysom, NOT FROM BEHIND, but in front of Taysom. Taysom is too big and fast for him to make the head on play, not to mention Taysom is laying a nice stiff arm on him. And it was nowhere near a horse collar tackle. At the 0:18 second mark the defender is still in front of Taysom pulling him down by his arm. Once again, nothing intentional or malicious here.