I searched https://turso.tech/blog/beyond-the-single-writer-limitation-... with ctrl-f for "download" and "--exp" and got no results for either. There was a link to a live demo webpage at the very end. Am I looking at the right blog? That's the one linked at the top of the page.
The flag is --experimental-mvcc, it is in the help for the shell.
You are right that the blog failed to mention. I will get this fixed soon!! Thanks for noticing it.
There is a lot of work that still needs to be done to make this production-ready, both from a performance and reliability point of view, as we did our best to convey on the blog. We truly appreciate you trying it out! Report any issues, please.