The video was real and had been sped up to last only 15 seconds instead of several minutes.
On Jan. 31, 2022, Reddit user OmarKage reposted a video on the r/Damnthatsinteresting subreddit that showed 10 pills burning on top of a stove. It appeared to have been posted after a Twitter account had uploaded it hours earlier.
The oldest version of the video that we were able to find was from April 15, 2021. However it didn't appear to be the source, which might have been a Snapchat story:
https://www.youtube.com/watch?v=V-fJiAKzETM
The speed of the video had clearly been increased, as readers could see by looking into the reflection of the top of the pan in the background, which showed a person quickly moving around. The clip only lasted 15 seconds, but its original speed likely lasted several minutes.
While we weren't yet able to find information on the source of the video, we were able to establish that it was authentic in what it showed. Reddit commenters were able to figure out that the pills burning on the stove matched other videos of experiments with calcium gluconate. It is used to treat calcium deficiency.
According to a video from MEL Science, which offers educational resources in the U.S. and U.K., a "gluconate snake" can be created with calcium gluconate:
https://www.youtube.com/watch?v=dwNbtLSYiEY
"Calcium oxide, carbon, water vapor, and carbon dioxide form. The water vapor and carbon dioxide froth the carbon and calcium oxide. The products of reaction 'crawl out' in the form of twisting snakes. It looks like the gorgon Medusa has come to life!"
YouTuber Taras Kul previously posted a video where calcium gluconate pills were burned on top of stove:
https://www.youtube.com/watch?v=IizC9f3X5m4
A YouTube account named NileRed Shorts uploaded a short video trying the same experiment with calcium gluconate pills being burned on top of a stove. "It breaks down into calcium oxide, carbon dioxide, and carbon, and it grows as a weird snake thing," the narrator said.
We found yet another video on the Danilaev RV YouTube channel.
In sum, the sped-up video that was posted to Reddit that showed pills burning on top of a stove was real, as were other clips of the same experiment that we found on YouTube.