At least they do in the Settings:

"The vertd project is a server wrapper for FFmpeg [...]"

I wish it were more common for open source licenses to have an attribution clause, like Apache does with its (optional) NOTICE files. When you put years of effort into a work, you deserve credit for it.

Edit: Actually, using a library via a package manager would likely be considered "linking" and not a Derivative Work, so I don't think even Apache's clause would apply in many cases.