You can only see HTML5 distributions in the SDL Media Manager mountpoint.
To publish from Media Manager to YouTube there is a specific YouTube channel where you need to add the assets too.
So if these assets are also in an HTML5 distribution, you can see (and use) these in SDL Tridion (you must have a Resolve ECL TBB which resolves the distribution to the YouTube URL, rather than the distribution URL, that is something you need to write yourself, or use my sample).
There is no way of publishing assets from Tridion to YouTube via Media Manager, since you only see distributions in Tridion and need to add assets to a channel for that. Since it is possible via the Media Manager API, you could write some code which does that, so for example a UI extension, which adds the assets in a distribution to the YouTube channel.