1. The 'init' hook is not recommended while registering the script libraries. So I updated the plugin by myself, and it works. Please refer to http://codex.wordpress.org/Function_Reference/wp_enqueue_script which mentioned that "by using the wp_enqueue_scripts hook (instead of the init hook which many articles reference), we avoid registering the alternate jQuery on admin pages, which will cause post editing (amongst other things) to break after upgrades often."
2. There is no way in the plugin to add my own jQuery library served on another CDN, so I have to modify the plugin by myself. It may cause setting losing if the plugin is being upgraded. Can you add a feature to let the user input the library URL by themselves?