Should you file copyright for your online videos, webinar presentations, email newsletter articles, blogs, SEO-ed Web pages, podcasts, white papers ... and the rest of the "content" your marketing department produces? Yes and no.
First of all, make sure all your templates (e.g., PowerPoint slides, landing pages, brochures, images, and podcasts) include a formal copyright line. Do this routinely at least once a year. It's disgustingly easy for the line to get outdated over the years, or to be eliminated during a revision or another format "upgrade."
These measures should deter or, at least, help battle situations when competitors, fraudsters, phishers, jokers making derivative material, and even unwitting consumers break copyright in ways that could hurt your brand. It helps you because you can say legitimately, "That material is copyright-protected and we'd appreciate if you didn't copy it in this particular manner or situation." A simple cease-and-desist letter can work wonders.
However, if your content is critical to your bottom line, then, you might consider taking the next step and officially registering a copyright with the US Copyright Office (link below.) What’s critical? You sell it as your product, it's heavily search-engine optimized and look-alike pages could hurt your rankings or, perhaps, it's the foundation of your brand differentiation vis-à-vis competitors (especially if you market substantially online).
The disadvantage is that it costs $35-$75 per filing, and you have to register each "publication" separately. There’s also a bit of administration work involved. The good news, however, is that you can register copyrights online. Also, once you've registered, your lawyers have a much easier time going after troublemakers and seeking damages.
I'm not a lawyer, so you should ask your legal team about copyright. In the meantime, here are some useful links: