udekimenage

At least the way |I learn Aikido, the techmnique should be able to break the arm, the combination of good Ukemi with the break possiblity, leads to a throw as Uke tries to escape your technique.

The break is oriented slightly up, so Uke will raise himself to escape, and would not be able to evade the technique with a single step.

This is not a simple technique, it takes lots of training in order to create force with varying vectors against his arm while only touching it at your elbow, without a grab.

As for the boxing Video
Very nice and couragious try, but you are missing the most important thing - you keep staying out of distance. As the puncher closes the distance, you must not retreat, rather you have to advance and get to his side, at which point you will find may opportunities stating to arise, in order to really get those chances, you should create Kuzushi and not by a grab&pull of Uke rather by understanding the center and positioning yourself accordingly.
The latter is not simple, and takes lot and lots of practice with slow punches, getting faster and more sophisticated as you progress.

Amir