I ran across this short instructional video. He says he jacks up to avoid the double hit yet the cb follows the ob down the table. Looked like a double hit to me. What do you think?
Impossible for that not to be a double hit. It's physically impossible for the cue ball to go forward like that unless it was pushed after contact. If you asked that guy to make the cue ball do that with the cue ball even an inch further away he would not be able to.
That being said, some double hits are more tolerated than others. As long as you jack up and or shooting at an angle, most leagues (and probably some tournaments) allow such double hits.