Useful...
Reading,
cooking,
capoeira,
dancing,
star gazing,
sun gaizing,
climbing a tree,
social skills,
sailing,
any and more of this activities would be useful when it come to anything that you do.
So, is capoeira useful for parkour..... If its moving you in any way, specially as capoeira is, up and down, spinning, pivoting, hand standing, crawling while keeping rhythm and flow...
Is tango useful for parkour....
The answer to both would be yes...
Think for yourself a little. Anything that benefit your body is useful for parkour. For yourself.