Creating HTML tables by hand can be painful, however thanks to orgtbl mode (which comes with org mode) Emacs users can edit tables in friendly way and later "send" (as org mode calls it) the data into a HTML source code. Inserting new columns and rearranging them is a single key binding!
What makes org (and orgtbl) mode even more powerful is the spreadsheet capabilities. You can define formula which will be used to calculate values of given cell or a group of cells (ie. a column). And because the underlying evaluation mechanism is Emacs' calc mode you can calculate almost anything! That includes integrals, differentials and Taylor's functions!
What else has been shown on the video is the spell checker and auto completion.