It's the same with (já) potřebuji / potřebuju
-u/-ou are considered more colloquial, -i/-í more formal.
potřebuji/potřebuju = 'I need' potřebují/potřebujou = 'they need'
Sorry, I made a typo. Edited now.
"potřebujou" is only dialects, grammatically right is "potřebují"! Do not teach foreigners bad Czech!
If I translated it correctly (I can't read that much Czech), it says that the -u and -ou endings are colloquial, not proper. It's interesting though, because the Russian first-person singular perspective does end in -u, and the Polish third-person plural perspective ends in -ą which sounds a lot like Czech -ou. So the common Slavic roots are evident.
I cant imagine pronouncing "potřebují" other than in formal occasions. I am from Bohemia. Even when teaching I'd say "potřebujou".
It doesn't. It says "hovorové", that is the spoken less-formal form of standard Czech. It is different from the colloquial or dialectal Common Czech or other dialects.
It is very hard to me to tell the difference in the sound of "Potřebuju" and "Potřebujou" it would be really nice and helpful if someone could explain the difference to me a bit :)