TMZ Sports has obtained video of Green Bay Packers rookie Aaron Jones' weed arrest ... showing the running back admitting he toked up before breakfast earlier that day.

Jones was initially pulled over around noon on October 1 for going 79 mph in a 55 when the officer smelled a strong odor and asked ...

"You gonna be straight with me or not gonna be straight with me? Weed."

Jones replied "I was smoking it."

"Yeahhh, there you go. I appreciate the honesty," the cop said.

Jones was then asked to take a field sobriety test ... which he bombed.