I've created a matrix report and I would like to know how to display it in my VF page using iframe. But I would like to be able to dynamically filter the report as users select different account ID from my VF page.
you can pass "pvX" parameter to the report endpoint to set the filters values. See this article http://jessealtman.com/2013/08/passing-parameters-to-a-report-through-the-url/ . E.g.
Hope this helps!