See here: http://jsfiddle.net/mm7Cf/4/

Type any text (or not), just focus on text input, and type enter.

Questions:

• Why it's the binding on the button which works?
• Why my binding on the form doesn't work?

If you remove the binding on submit button, my form binding works.

If you remove the binding on form, the submit button binding works, EVEN IF I do not click on the button, just submitting it when focusing on text input and type "enter".

In my opinion, it's not the wrong behaviour.

Typing enter on text input focused should only execute bind on form.