There are two types of bots:
Bots that have control over a webbrowser (the bots in the videos)
Those bots are slower because they have to render the webpage
But therefore the developer can directly work with the page (execute javascript and inspect the DOM)
That makes creating and maintaining these kind of bots easier
The developer can also hide the "webbrowser window" from the user
Those bots are cheaper, because they can be created faster
And there are bots that work directly with webrequests
Those bots are faster because they just send the requests (http header + body)
But the developer has to manually figure out what the javascript does and replicate the behaviour of the site
That makes creating and maintaining those bots harder
If you want to scale your campaings (with multiple accounts/proxies/...) you will need this kind of bots
But those bots are also more expensive
Im not agree. (And i develop some bot builder tool).
In first place in the bots that uses some instace of the browser there are some thing called headless browser, this means a browser that does not show up but render the page.
Could take more time but its more precise, much more effective.
The other browsers just download the HTML code but dont render it (and dont run jquery, javascript, glash, etc) so are very limited and fails much more often since it can do not detect many things.
Its very important today to render the page and to run all the additional scripts, plugins, etc. that a browser can run, because most web 20.0 pages and social ones uses a lot, you are going to fail a lot if you do not render the page and are capable of render flash, jquery, etc.
The idea of a bot is to replicate some task that people can do in a browser, but extracting information from some text fie, per exmaple, for filling the info needed and also can store the results (images, data, etc). Per example a bot that creates accounts.
If the page uses jquery, in general, the only way to being sucessfully, is rendering the page and running javascript, flash, etc.