Why are we here, What are we striving for?

for a specific downloader you remember. Troubleshoot why your current version isn't working.

If you are looking for an actual rather than the player, version 2.1.6 of the popular Video Downloader app is a common search.

Downloading YouTube videos violates YouTube’s Terms of Service (ToS). While version 2.1.6 is an old tool, the act is still against ToS. Moreover, using abandonware that bundles codec packs without licenses could expose you to copyright infringement claims.