Techniques for monitoring an online video advertisement system include receiving a request for insertion of an online video advertisement, determining, selectively based on presence of a debug suffix, whether the request includes a debug request, performing a bidding auction to select a winning bid, and sending debug information, in response to the request, upon determination that the request includes the debug request. The debug data includes bid data received during the bidding auction. In one advantageous aspect, the use of hypertext transfer protocol headers to communicate debug information allows for activation and deactivation of the debugging operation transparently, e.g., without changing the underlying application layer workflow.