I think we can all agree that Amir Khan's performance seems implausible. Everyday experience shows that a puff of smoke, etc, is quickly dissipated in the surrounding air. Even if a parcel of air is enclosed in a light membrane, as in a party balloon or a soap bubble, air resistance would prevent it being projected very far, no matter how fast the initial impulse. I doubt that even a professional baseball pitcher could project a party balloon more than a few feet though the air.
On the other hand, the example of the vortex cannon shows that there are exceptions. Some people have concluded that the Khan videos must be faked using a vortex cannon. The conclusion does not follow unless all alternatives have been excluded. To test one alternative, this morning I tried blowing out a candle from a distance using an ordinary hand-held hair dryer. The dryer, a Braun Professional 1800, has a power of 1800 Watts (some of which goes into the heating element) and a nozzle presumably designed to focus the air flow. Using the dryer on full power, but with the heating element turned off, I found it very easy to blow out a candle at a distance of a metre. At 2 metres it required a little practice to get the air blast on target, but it was then effective. At 3 metres it was more difficult, as the flame flickered but was very reluctant to go out. Several times I thought it had gone out, but when I turned off the dryer the flame recovered. I did eventually succeed by holding the blast on the flame steadily for about 8 seconds. Incidentally, the candle was a flat night-light or tealight, and a taller candle, with a more exposed flame, might behave differently.
I was surprised that the dryer was quite effective at 2 metres, and even had some effect at 3 metres. I do not know if some kind of vortex action is involved. And if this was possible with a small hair dryer, imagine what might be possible with something more powerful, like an industrial space heater or a leaf blower. Assuming that the Khan videos were faked, I suggest that a leaf blower is the most likely implement to have been used, simply on grounds of availability.
Of course this does not show that the Khan videos are genuine. I would say the case for fakery is plausible but not proven. I do not see anything in the videos to suggest that they are
intended to be seen as anything other than genuine exercises of skill and speed, which is how they were generally presented in press reports. But I was wrong to describe it as his party trick.
This is his party trick: juggling a bottle in the air with his fists:
Source: https://www.youtube.com/watch?v=_KM6khEPSnA
But some people think that is faked too.