These folks all have great input. I hope you don't mind my adding a few thoughts from my own perspective since you seem genuinely interested in gathering input on the format?
The "AI" narrative concept did make it far more lore-friendly to consume but was also slightly distracting.
The script's terminology was all over the place. For example, Blasters: "They sometimes blast again and again". What does this mean to a casual or new player? Increased attack speed for a time? Multiple hits on one target per single attack? The writing could definitely have had more clarity in a few spots to strike that balance between informative and easy-to-digest.
That said, having the various effects explained in layman's terms was still a spectacular approach. TFT is a great pick-up-and-play game, and I've seen quite a few casual players pick it up who have no interest in or knowledge of League itself. Videos scripted like this are great for that sort of player and really makes it feel more accessible.
Unrelated to the minor writing nitpicks, it looks like the team's put a lot of work into making the video clear. Not once did the CC/Subtitles cover any important information/caption/animations as far as I could spot, unlike a few other videos Riot's put out in the past which didn't seem to take the possibility into account that the bottom 1/6th of the screen might be covered at any given time.
Also of note, whoever on the team decided that using that specific arena skin was a good idea for the video deserves a free coffee. The darker violet contrasts perfectly with the goldenrod accents on the animation. It pulled the eye exactly where it needed to go as the video progressed. Perfect use of color. Thumbs way up.
Thank you for the very thorough response! I'll be sure to pass along the script feedback to our writer. Glad you had parts you really enjoyed :)