With the recent major update, Freetube implemented a new player which I like much better than the old one. With the new player, all keyboard shortcuts work well, that’s great for me because my Home Theatre PC is controlled by a wireless keyboard+touchpad.
I agree, F5 would have been better since it is the standard on Linux and Windows. The only reason why I found out is because I’m used to do cmd+R on Mac (I use Mac at work so I got familiar with it).