1. A method for inserting a multimedia file through a web-based desktop productivity application, comprising: receiving, at a first server computer, a request for the multimedia file from a client computer over a network, the client computer configured to display the web-based desktop productivity application via a web browser; upon receiving the request for the multimedia file, transmitting the request for the multimedia file from the first server computer to a second server computer over the network, the request for the multimedia file being transmitted via a proxy web service executing on the first server computer, the proxy web service configured to circumvent cross-site scripting security measures on the web browser; receiving, at the first server computer, the multimedia file from the second server computer over the network upon transmitting the request for the multimedia file, wherein receiving, at the first server computer, the multimedia file from the second server computer over the network upon transmitting the request for the multimedia file comprises receiving, at the first server computer, the multimedia file at a receiver web service executing on the first server computer, the receiver web service configured to forward the multimedia file to the web-based desktop productivity application for inserting into the document, wherein the web-based desktop productivity application inserts the multimedia file onto a placeholder within the document, the placeholder being specified by the client computer; and inserting, at the first server computer, the multimedia file in a document edited by the web-based desktop productivity application.