Agreed. Anything that interrupts the usual rectangle is a problem because there's no "safe space" that anyone can know for certain will never contain important content. Classic example: Those scrolling text lines at the bottom of many TV news programs. They're often RIGHT OVER THE TOP of some similar text content in the existing video they're using as part of their report! Likewise the network's own logos or "promo pieces", often in the lower right corner... where they typically stack up over the logos/thumbnails of the content itself. Add in partial transparency (itself an admission of the stupidity of this concept!) and you get some weird Pollock-like renderings that are utterly unintelligible and completely frustrating.
A far better approach, if someone insists on stealing some screen real estate, is to downscale the image (to maintain the aspect ratio) and put your content in the created black space. Sure, it's still a visual interruption and maddening, but at least they've respected the original content (which is the reason you're a consumer of their product!) while satisfying whatever corporate overlords have demanded their own content be displayed. I see this a fair bit... the main image shrinks for a few seconds, some sort of nonsense content appears, and then the main image zooms out to the original size. That's an intelligent way to handle this.