You can download all OCJN videos from here. It is a file sharing service from my country, risk free. You can click on "STÁHNOUT VŠE JAKO ZIP" which means "Download all as ZIP" and it does exactly that. All together, it is around 14,5 GB
<br>

https://www.uschovna.cz/zasilka/TPZ2JIIGB8AD9LZX-TE3/2H4KZJ3MFW
<br>
Or you can use alternative link: https://webshare.cz/#/file/YlLZu6Cdnv/ocjn-zip