Why did the clock stop after the Williams catch?

[DTVietnam]

Originally Posted by DaFace

You're not interpreting the rule correctly. If a guy shoves you to the ground, you're down. You don't have to be touched while you are physically on the ground.

But it seems the ball was not secured till he was on the ground?..so it wasnt a catch until he secured it and at that point he wasnt touched . .right?

Like when Tyreek caught that ball in the comeback against the Donkeys and his knee was down and he was touched but didnt gain possession until he was in the endzone:

skip to 8:45