Diablo 1 HD Hellfire Mod | Awake

I hardly ever use this spell, but when I used it just now as a warrior, it apparently instant casted for me despite not saying "Instant cast" like the Flash spell, in the spell book.

Is it supposed to be an instant-cast spell, or is this a bug?

it's just surprising, since the regular Lightning spell has the full cast time. (820 cast time, with standard 100% cast time)

Can you make a video? If you consider it a bug, is it reproducable?

Here's a video showing a couple spells with my normal casting speed, and then chain lightning.

https://www.youtube.com/watch?v=6STcyWsS0xg

Edit: if it's possible to embed videos on this forum, how do you do so?