The URL filtering engine will log all GET requests, assuming that you have a URL filtering profile minimally set to "alert" for that category. That said, depending on the "log container page only" setting, we may only log URLs of a specified content type. This feature is meant to reduce the number of logs that are generated (mostly images and other code that you may not find useful). If, however, you do want everything logged, simply disable container page logging. As mentioned in sdarapuneni's post, if you've enabled container page only, it will only log URLs of the specified content-type. So for example, if you set container pages to only content type image/gif, then in your example above, you would only see log entries for the .gif files.
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