Web authors in few or some, have added illustrations on another web page or within the chapter. This made me wonder what differences would there be if web authors apply GIF for scenes that are hard to describe and emphasize with words alone. Though if these web authors practice continuously to develop and sharpen their writing skills, then there wouldn't be the need of GIF or excessive amount of illustrations. Do not click if you have epileptic symptoms. Spoiler: Example GIF There was no need for a logical reasoning. There was no need for a reason as to why such an event happen. There was no need for him to consider the possibilities of whether he made a mistake or not. There was no need to even think currently. There was no way for him to regret his decision as he was at the brink of insanity. A repulsive sensation was continuously invading every fiber of his self. It was violating all that reminded him of his humanity. It continued to savor his essence. An essence that every living human was born with in world. His soul was slowly being devoured inch by inch by a demonic presence. His very being that made the world recognize him as a human was fading without him being to resist. Resistance was futile, since it seemed to make the process more agonizing as the demonic presence invading him preferred that he resisted. It was twisted beyond human rationality as it took pleasure at his struggle and suffering.
Ok, If I tripped over that kind of crap in a story, I'd delete that tab and block the site. I tried reading your blurb under the flashing GIF, and it was a pain in the ass. I'm all for mixed media, but it needs to be harmonious and complementary, not smack the reader in the eyeballs. Even static pics in the middle of sories (I'm looking at you Average) can break the flow and distract from the immersion. To put it in another perspective, you might as well write a story filled with blink tags. Besides, while a picture may be worth a thousand words, typing those words is far faster and cheaper than making your scenes in a GIF.
In the page automatically playing? No. Either have a clear link to it on a hosting site, have an appendage number and attach it to the bottom of the chapter, or have it hidden behind a drop down window like the spoilers tag here.