Yes you should be able to do it.
When you go to your talk and select the timeline (submenu on the right) then you`ll get a menu
on the top left which is basically your media library. There is a tab youtube. When you go
there you can click on the small plus sign at the bottom and paste in a youtube id. This
will import the video into your library. The you can drag&drop this video to the timeline.
Then you start adjusting your slides… Don`t forget to save your changes (button at the bottom of the timeline) when you`re done.
Again it`s all still a bit beta but this will improve soon!
Let me know if this works for you.
Benjamin