Zero!
presto
in 1785
Bonn, Germany.
No. He doesn't have any kids either.
march 16 1781
Yes!
Rocket Gibraltar
There does not seem to be any newsworthy video tutorials for kids started by a grandfather. If there are more details about the video, it may be easier to look for.
The children of your great grandfather's brother are your grandparent's first cousins, and your first cousins twice removed.
Just add "pra" prefix to "dziadek" (eng. grandfather) for as many times as many "greats" is there. Great grandfather = "Pradziadek".
Ludwig Van Beethoven
Jens Oestergaard has written: 'Beethovens klaverkoncerter'