He says air wooshes out of a slit in the tire, unless he compresses the tire with his hand. Then it holds.

This implies at least two things:

(1) His tube leaks air, but his rims, spoke holes, etc. do not.

(2) Compressing the gash in the tire magically seals the tube, as well as the tire.

(If there is any truth to it, he might have a leak at the valve stem/tube interface, which, when correctly positioned, doesn't leak as much.)

But I am reasonably confident the whole thing is bullshyte.