"Online generators" – not sure if they want to replace this with alternatives. Maybe "generator tools" / "serial number creators" / "key generators". But the user specified proper nouns only shouldn't be touched. "Online generators" is a common phrase, so replace with web tools.
When discussing "4K Video Downloader", the synonyms are already a proper noun, but "software" could be application. Platforms like "YouTube" and "Vimeo" are proper nouns, so they stay. "4K, 1080p, 720p" can be replaced with standard definition as the resolutions. 4k Video Downloader Serial Number -UPD-
Next part: "the full version of the software." "Full version" could be replaced with complete edition / premium version / unrestricted mode. So premium mode. "Online generators" – not sure if they want