I haven't had issues embedding videos side-by-side when using YouTube or when uploading media, as long as the video dimensions are small enough to fit side-by-side in the window. If I shrink the window, they will stack when they become too big to fit side-by-side. If they stack when I'm adding them, I will put my cursor to the left of the embedded video and delete until it is side-by-side with the one above.
Oh geesh, you are right! It is just that simple.
Has something changed in the new RCE, or did I just missed that for the last 5 years?? LOL