Yes, I have played snooker about twenty times. What makes a 147 break so rare is that the reds, which begin in a triangle formation, all need to be developed, and doing so without ever losing position onto the black is very difficult. The feat can be done in competition or in a practice match. Solo practice with a full triangle of reds can be done, but requires that safeties are played until there is an opening of some sort. This gives you practice in both safety play and in break building in a typical game situation.
The drill presented here is excellent practice, but it's a drill. The drill covers some, but not all, snooker break building skills, most notably omitting developing the reds. The nine ball ghost is also a drill. A ten pack against the ghost should not be confused with a ten pack and nobody having any integrity who runs a ten pack against the ghost would ever dare make the claim of having run a ten pack without qualifying that claim by saying that it was against the ghost.
Although one can score them if they choose and in any way they want, drills are not scored in the same way as ordinary racks of pool or frames of snooker and when one talks of a run in pool or a break in snooker, one is not referring to the completion or partial completion of a drill. That's what's false about the thread title. If I do a drill, I might record that I completed the drill successfully on two of my ten attempts, but I'm not going to count each ball made consecutively as if it were a run. That would misrepresent and overstate my accomplishment.
I have already said that this kid's accomplishment is extremely impressive, even calling it mind-blowing, and I said that he shows great promise, but the thread title misrepresents his accomplishment. He scored 147 in a drill, and did not score a 147 in practice, which means something completely different.