Stall Speed?

I've noticed that when you turn a torque converter with your hands, the input shaft does not turn. I've tried to do a little research and wanted to ask, is this so because of stall speed? And if so, can someone give me their thoughts on the concept of stall speed? Another question that had me to thinking was how fast in rpm would the torque converter need to spin before the input shaft spins, what variables are there? Thanks

Thanks, I checked out the video. I had meant to say 'output' shaft in my post but nonetheless, think i've got an idea on why it did not turn from watching the video. From what i gathered the action really does take place inside the torque converter with the impeller, turbine, and stator. It makes sense now that unless i'm bruce lee, me turning the torque converter by hand would not be fast enough to 'make the action' happen inside the torque converter in order to see ouput shaft spin.