Cool build there. Nothing new though.
Except that it's powered by a bike instead of a motor.
Same concept on baseball batting cage launchers.
And another for footballs where the ball is fed in on a tray to slide the ball in from the back. Those had larger wheels (pneumatic tires for industrial wheel barrows or carts).
Cool that it's aimed by the handlebars.
The friction on the ball is for such a short duration, perhaps if it just smacked them (like a bat) they may go faster even.
(Unless it was firing something longer).
I was looking at a physics text book that showed the "sweet spot" on a baseball bat slightly lower than the tip. (Well known by baseball greats). Interesting.
I often wonder what people were thinking long long time ago while using foot powered sharpening stones or the first lathes (also pedal/foot powered).
BTW, If something longer was launched this way,There's a way to accelerate it even faster/further after it leaves the wheels (against rules to discuss, besides...)

8)