The YouTube ECL provider on Tridion World has the source code in the package zip, which you could update to use the newer YouTube API.
The provider was created for a specific project and hasn't really been looked at in a while. When I get a chance, I'll have a look at updating it to the newer API.
However, I can't promise when this will be, as I'm working on other projects currently.
I have put the code up on Building Blocks' Github organisation and I'm very happy to accept pull requests for it.
You'd need to remove the YouTube GData nuget package, and its dependencies and install the newer Google APIs Client Library, making any necessary changes to the code.
There are some good code samples samples on the Google Developers site.
Sorry I can't give you an updated version, but hope this helps.