Which package shall I choose?

Basically that's depending on your budget and to what extent you'd like to have control over the chat client.

If you're representing a large company and have enough budget, and if you prefer to have domination over the software license and want to have overall control over the chat client, you should definitely go after the full package: 123flashchat license and video chat module, then you may host the video chat by your own. You can also choose the yearly hosting package if you'd leave all the setup and maintainance to us. If you're the owner of a low budget small website, you may start with having us host text chat and video chat because our price is quite cheap in the video chat hosting business.

If I buy text chat for 250 user max, and video chat for 50 user max, then how many people can chat at the same in my chat rooms?

In that case, all people in all your rooms can't exceed 250, while only 50 video windows can be activated. When the 51th person try to publish his video, he will get error message which says "try again later". That's not very friendly, so we strongly recommend you to synchronize the text and video chat hosting levels.