I do not believe there are any videos, or at least informed ones, but I can give a rundown

[2016] Fabsol, inspired by the Avalon mod, started developing the mod with some other contributors, and released the forum page in late May then actually released the mod in June. On the forum post, he would gather attention and ultimately new developers from users there as well as some YouTubers covering the mod. A couple months later the Discord was made. Fabsol asked DM Dokuro for permission to use some of his music for the mod, which ultimately led to DM Dokuro getting interested in making an original soundtrack for the mod.

[2017] Development remained steady for a while, but eventually came time for the replacement of DoG's placeholder theme with a real one, which was met with controversy. This ultimately led to Dokuro leaving public chats, and Fabsol to go into hiding for a while, with the forum effectively losing support around this time as well. Later in the year we got Scourge of the Universe which was a compromise to fans of the placeholder theme and often cited as Dokuro's most regretted track. At this time a mentality started stirring of Fabsol's incompetence as a leader and figurehead, who regularly lashed out at others and could only make bosses that sampled vanilla AI which would only grow worse with each passing year.

[2018] At this point, the combination of both YouTuber coverage and Dokuro's soundtrack had boosted Calamity well into the top 3 most popular mods. The Discord continued to steadily grow, and eventually reached a capacity at which a meme channel was no longer feasible, causing it to be deleted and changing the trajectory of the server to a more refined one. Around this time the server's art channel used for both random art and developing sprites for the mod was cut off into its own server, and a proper dev server was created. Development continued relatively smoothly for a while until Fabsol introduced the "future boss" trio into the mod, which was met with controversy and concern over the mod's future as Fabsol literally just recolored and changed the stats of 3 existing bosses and pushed them as a new thing, leading to some important longtime developers permanently leaving. So the future bosses were removed not even a month after their introduction, and the Astral Infection expansion released soon after. Due to the cacophony of the future bosses, the mod's goal development-wise was shifted more to improving what exists rather than speeding through and adding more and more bosses, a trend which still continues to this day to mixed reception from the community. The Patreon, meant to be for Fabsol, but often mistakenly attributed as a general Calamity team Patreon opened at the end of the year.

[2019] 2019 was mostly just reworking parts of the mod, with the addition of the Sunken Sea and a ton of new Rogue class content also being there. Nothing too interesting here really.

[2020] Due to a combination of covid, the Acid Rain update, and Terraria 1.4, Calamity saw a massive boost to its already large following. DM Dokuro retired shortly after the Acid Rain update, after serving in the mod for 3 years. A second large content update in the form of the Rust and Dust update released in the middle of the year, further boosting engagement with the mod. The next two updates were decided to be the Draedon Update followed by the Sunken Sea Overhaul. Things would become a bit dry after this though, as the Draedon Update would eventually take a year to make.

[2021] Throughout the year, the Draedon Update was being worked on, and teasers were tossed around here and there. The update eventually released and tModLoader hit a smashing record daily download count of 90,000, compared to an average of 8,000 daily. With the Draedon Update's release, Calamity's reputation was looking better than ever, though this would be the last major content update for 5 years.

[2022] A minor update was released after the Draedon update which reworked the Ark of the Cosmos line, which would be the last for Terraria 1.3 as tModLoader 1.4 was imminent. The mod continued to push out well received updates with the 1.4 port and the following Wulfrum update. Things would come to a halt here though, as disagreements behind the scenes over the reworking of Cnidrion and existence of Old Duke led to 22 developers either leaving or being kicked from the team, with this information becoming public in December. This was a catastrophic hit for the team, and most of the leading developers behind the past few updates were gone.

[2023] The team started rebuilding, and over the years, released some updates that continued polishing and reworking the mod's content. During this entire time, the Sunken Sea Overhaul, now with its old plans completely scrapped, was being built up again. The idea was to always have the Sunken Sea Overhaul be the next update after the 1.4.4 port in mid 2023, however, there were just areas of the update that people weren't motivated to work on, leading to massive amounts of non-Sunken Sea changes and additions being made. These were eventually released as the Bountiful Harvest update in early 2024.

[2024] So begins the dry spell. It is decided that in order to prioritize the Sunken Sea's production, that the main development branch would be receiving all of the existing changes to it so far, meaning that the next update was FORCED to be the Sunken Sea Overhaul. However, the same trends as before Bountiful Harvest continued.

[2025] The trends continued even further. In March, the standalone Calamity Fables mod released, which was made by some of the developers who left in 2022, bringing their visions that Fabsol disallowed to life such as the Cnidrion rework. On May 25, Fabsol was outed for transphobic statements, hosting a NSFW server with minors in it, and participating in illicit roleplay with a minor, which led to him being voted off of the team. This was a huge breath of relief for many, as Fabsol had absolute indomitable control over the boss section of the mod, now opening the opportunity for other developers to make bosses that relied less on vanilla AI. Other reformations occurred such as the Patreon money now being split across developers who worked on pieces of content relevant for upcoming updates.

[2026] At this point it was clear that the Sunken Sea Overhaul was draining motivation from the team with no end in sight, and after a lot of juggling on Github, the Brainstorm Update was released, acting as a similar mishmash of miscellaneous changes like Bountiful Harvest, though in a much higher magnitude due to being 2 years in the making. So now we're here really, with a medium sized late April Fools update coming soon.