What I believe happened in the video between 1:00-1:07 is manual data entry for all of the available appointments for that date. There was no formula that auto populated the table. Airtable is different from excel/google sheets where you cannot have a formula that you can drag to continue to add 5 minutes to the cell beforehand for example. All formulas apply to the entire column in Airtable rather than individual cells as in excel/google sheets.
My recommendation for populating your table in a more efficient manner is either to ask ChatGPT to create your data set for you, or to create the data set in excel first, and then you can copy and paste your data straight into Airtable. You can prompt ChatGPT with something along the lines of "please create a table of appointments in 5 minute increments for xx day between 12-5pm for 4 different rooms named A, B, C, D "
I hope this helps, please let me know of you have any questions.