YouTube has changed their API again… The YouTube2 and YouTube Cast Receiver plugins utilise the awesome ytdl-core library for some parts of data retrieval, and I believe a fix is underway for that library. When that happens, I’ll update said plugins to use the updated version of ytdl-core.
Having said that, I would still need to implement a workaround to make sure the updated ytdl-core library will work with Volumio 2.x, because even the current version of that library has dropped support for the legacy Node 8 which Volumio 2.x still uses. This is going to take a bit of time and unfortunately, I don’t have much time on my hands recently. I’ll get to this ASAP.