Play 1
NFHS - Arguable but no flag ( runner fell forward not backwards, you could argue its to the side but that would be the only way)
NCAA- Absolutely not ( was not immediate + logic from above)
While I don't think this was a forward pull, it doesn't matter. Under NFHS, the direction no longer matters.
9-4-3k: Grab the inside back or side collar of the shoulder pads or jersey of the runner
and subsequently pull that opponent to the ground
If you can grab the back or side of the collar and pull him any direction, it's a foul.
Under NCAA, that's close enough to immediate, there is a grab, a jerk, a quick release and a fall all within in a second or so of each other.