Chaturbate is not an agency, it's a platform for solo webcam models. They don't force anyone to work for them, they don't hold anyone captive either. They simply provide a platform to stream yourself online in exchange of money.
Most models are from poorer countries, mostly Latin America or Eastern Europe, where sex trade, women exploitation is a real issue. There are solo models, then there are big houses, flats, where many models work together and obviously all of those are run by someone. There's an
article on vice.com about Romanian studios (they called these studios) and according to the article, there were 2,000 studios just in Romania at that time (6 years ago). If 10 models worked in each, that's 20k camgirls/guys working from studios in just one country. Mind blown. It's big profit too, a studio with 15 male models turns over 50k EUR per month according to the article. And those are guys, girls make twice as much.
I have not seen any of such videos you mentioned, but i can imagine, some of these models might not be doing this willingly. It's the adult industry, shady stuff is not a rarity. Sad, but true. This is very far from the subject of this thread though.