How to Hack a Server Based Encrypted Pen-Drive?

Some video lecture providers have started using this kinda technology where one has to type-in the login details to get inside (An internet connection is necessary).

Their videos are encrypted in some other format which can only be played by launching a special software that they have created.

Is there any way to bypass the server login and remove encryption on the video files, so they can be extracted out?

I could not find anything related to this topic on the internet, if there is, please provide some links.

My primary objective is to extract the data from drives which isn't allowed!