Again, thank you for the video.
If you can use the Generic Bluetooth Adapter Driver with the Dongle but not with your Internal Bluetooth Adapter, I'm guessing they are not compatible. It is recommended that you continue to use the Dongle.
The button you are clicking is for scheduling. It will search the surroundings for biosignalsplux devices that were previously added to the software and, if any found, it will let you schedule an acquisition to the internal memory card. Since you have a BITalino, you cannot use this function.
I believe the button you are looking for is the one that has a magnifying glass on it. When you click on it, OpenSignals will search the surrounding for any plux device that is able to acquire bio-signals. Once done, it will let you add one of the found devices to OpenSignals and configure its settings. Clicking the Record icon will start an acquisition with the Enabled devices.