how to setup rule events for before/after video is played?
When video start/end it should call js function which trigger ajax call for path you create on drupal (using hook_menu) the callback of that menu item should call the rule you want using rules invoke function 
    rules_invoke_component('rule_name', $arg);

So the case is how to trigger the ajax call on start/end

if you are using youtube, check this page, you can trigger js function to start the ajax 

https://developers.google.com/youtube/iframe_api_reference

if you have another player you should look to the api